Boiler Error Codes

Worcester Bosch

Worcester Bosch CDI Classic Combi Boiler Error Codes
Fault Description	System Behaviour
A1	Water is leaking or the pump needs replacing or freeing due to the pump running dry.
A7	The hot water negative thermistor coefficient (NTC) sensor is defective – the hot water sensor or connecting leads need checking.
A8	Break communication to FX sensor controls electrical connections need checking.
B1	Code plug not detected .
C6	Fan speed too low – the fan lead and connector need checking and may need replacing.
E2	Central heating (CH) water flow negative thermistor coefficient (NTC) sensor defective check CH flow NTC sensor and connection leads.
E9	Safety temperature limiter in central heating (CH) flow has tripped the system pressure or safety temperature limiter needs checking
EA	Flame not detected due to a gas issue – the gas supply, power supply or igniter, electrode and lead need checking – contact a Gas Safe installer.
F0	Internal error – electrical connector contacts or programmer interface module – check ignition leads are not loose.
F7	Flame detected even though the appliance is switched off – check the electrode assembly is dry and the pcb and flue are clear.
FA	Flame detected after gas shut off – the gas valve needs checking – hire a Gas Safe installer.
FD	Reset button pressed by mistake – press reset button again.
Worcester Bosch CDI Highflow Combi Boiler Error Codes
Fault Description	System Behaviour
A1	Pump dry run detection or pump is running in air the system pressure needs checking
A5	Tank negative thermistor coefficient (NTC) defect
A7	Domestic hot water (DHW) negative thermistor coefficient (NTC) defect
A8	Energy Management System (EMS) communication error
B1	Code plug not detected
B2, B3, B4, B5, B6	Data error
B7	Burner control error
C6	Fan defect
D3	External temperature limiter
D5	Condensate pump failure
D6	Internal heat bank overflow
EA	Flame not detected
E2	Primary negative thermistor coefficient (NTC) defect
E9	Safety temperature limiter in central heating (CH) flow stat tripped
F0	Internal error
F1	ROM fault
F7	Flame detected after appliance has been shut off
FA	Flame detected after gas shut off
FD	Reset button pressed – try pressing the reset button again
Worcester Bosch CDi Compact / Greenstar 25/30 Si Combi / Greenstar 27/30 I system Boiler Error Codes
Fault Description	System Behaviour
T1	Ignition test – checking the igniter spark
T2	Fan test – checking the basic fan
T3	Pump test – checking the basic pump
T4	Three way valve test
T6	Ionisation oscillator test
9A 362	error – incorrect HCM fitted
9U 233	Heat Control Module (HCM) error – problem with code plug
B7 257	Internal error – possible control board problem
C6 215	Fan problem – fan running too fast
C7 214	Fan problem – fan not running
D1 240	Return sensor error – sensor may be wet or damaged
E2 222	Flow sensor short circuit error
E5 218	Flow temperature too high
E9 219	Safety sensor fault – temperature too high, sensor short circuit or open circuit
EA 227	No flame detected or flame signal loss during operation
F0 237	Internal error
F7 228	Flame error – false flame or flame detected before burner started
FA 306	False flame fault – flame detected after burner stop
FD 231	Mains power fault – electrical power interruption
FA 364	Gas valve EV2 leak test failed – gas valve leak
FB 365	Gas valve EV1 leak test failed
A1 281	Pump stuck or running with air in the system
C1 264	Airflow stopped during operation
C4 273	Airflow present during last 24 hour
D1 240	Return sensor short circuit
D4 271	Temperature difference between flow and safety sensor exceeds limit
E9 224	Max thermostat activated – flue gas thermostat overheat
EA 227	No ionisation detected after ignition
EF 349	Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return.
NO CODE 212	Safety or flow temperature rising too fast
Worcester Bosch CDi Classic Regular Boiler Error Codes
Fault Description	System Behaviour
B1	Code plug not detected
C6	Fan speed too low
E2	Central heating (CH) flow negative thermistor coefficient (NTC) sensor defective
E9	Safety temperature limiter in central heating (CH) flow has tripped
EA	Flame not detected
F0	Internal error
F7	Flame detected even though appliance switched off
FA	Flame detected after gas shut off
FD	Reset button pressed by mistake
Worcester Bosch Greenstar I System / Combi Boiler Error Codes
Fault Description	System Behaviour
226	Service tool has been connected in the blocking error history menu
FD 231	The power has been interrupted during a lockout
C7 214	Fan does not run during the start up phase – fan harness connector needs checking
C6 215	Fan speed too high – check the fan harness and connector
C7 216	Fan speed too low – check the fan harness and connector
C7 217	Fan has stopped during appliance operation
C1 264	Fan stopped during operation
C4 273	Continuous fan operation for the last 24 hours – appliance temporarily blocked
E2 222	Flow temperature sensor shorted
E2 233	Flow temperature sensor disconnected
E9 276	Primary flow temperature exceeded 95°c
E2 350	Flow temperature sensor shorted
E2 351	Flow temperature sensor disconnected
FA 306	Ionisation detected after the gas valve closed
EA 227	No ionisation detected after ignition
F7 228	Isioniation current detected before burner start
EA 229	Loss of ionisation signal during operation
EA 261	Heat control module (HCM) potentially defective – reset the appliance
9U 233	Control box or heat control module (HCM) is defective or loose, the HCM needs to be checked
C4 237	Control box or heat control module (HCM) is defective
F0 238	Gas valve or control box error – gas valve coils need checking
F0 239	Control box or the heat control module (HCM) is defective – the control box connections need checking
F0 242	Control box or the heat control module (HCM) is defective – the HCM and control box connections need to be checked
B7 257	Control box or the heat control module HCM) is defective- the HCM and control box connections need to be checked
F0 258	Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
EH 258	Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
F1 259	Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
F0 262	Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
F1 263	Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked
F0 272	Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing
F0 280	Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing
F0 290	Control box is defective – HCM needs checking as it might not be inserted properly or need replacing
328	Internal error with the mains voltage – frequency may be inconsistent
235	Incompatible heat control module (HCM) software versions – control box needs latest software
356	Low mains voltage – the voltage may be interrupted or inconsistent and needs checking
360	Heat control module (HCM) invalid – the inserted HCM does not correspond with the control box
A8 362	Low mains voltage – the voltage may be interrupted, inconsistent or heat control module (HCM) invalid
CC 800	Outdoor sensor defect available when accessory outdoor sensor is connected
A1 281	Pump stock or running dry
E9 224	Flue or high limit thermostat activated
D4 341	Primary flow temperature rising too fast
Worcester Bosch GB162 Boiler Error Codes
Fault Description	System Behaviour
208	The boiler is in chimney sweep mode
200	The boiler is in heating mode
201	The boiler is in domestic hot water (DHW) mode
202	The boiler is waiting – there was a heat demand from the on off or modulating control
203	The boiler is on standby
204	The boiler is waiting – the actual temperature is higher than the calculated or selected boiler temperature
212	The temperature recorded by the flow temperature sensor or the safety sensor is rising too quickly
226	Diagnosis tool was connected and is now locked out
260	The flow temperature sensor is not detecting a rise in temperature following a burner start
265	The boiler is waiting in response to a heat demand – the boiler regularly switches to partial load
268	Component test phase
270	The boiler is modulating upwards
283	The boiler is preparing for a burner start – the fan and pump are activated
284	The gas valve is switched
305	The boiler is waiting for domestic hot water (DHW) operation to end
235	The KIM (boiler identification module) is too new for the burner control unit
360	The KIM that has been fitted is not compatible with the burner control unit
9A 361	The burner control unit that has been fitted is not compatible with the KIM (boiler identification module)
9U 233	The burner control unit or KIM (boiler identification module) is faulty
A3 317	Short circuit in the flue gas temperature sensor contacts
B7 257	The burner control unit or the KIM (boiler identification module) is faulty
C1 264	No control signal or power supply to the fan during operation
C4 273	The boiler was switched off for a maximum of 2 minutes because it had been operating continuously for more than 24 hours
C6 215	The fan speed is too high
C6 216	The fan speed is too low
C7 214	The fan does not run during the start phase
C7 217	The fan speed is irregular when starting up
CE 207	Water pressure is too low
CE 266	Pump test failed
D1 240	The contacts of the boiler return temperature sensor have been short circuited
D1 241	The contacts of the boiler return temperature sensor have been interrupted
D3 232	The external switching contact has opened
D4 213	The actual temperature recorded by the flow temperature sensor or return temperature sensor is rising too quickly
D4 271	Actual temperature differential between flow and safety temperature sensor is too high
D4 286	The boiler return temperature sensor has detected a return temperature higher than 105°c
E2 222	Short circuit in the flow temperature sensor contacts
E2 223	The flow temperature sensor contacts have been interrupted
E5 218	The temperature captured by the flow temperature sensor exceeded 105°c
E9 210	The temperature measured by the flue gas sensor is too high and is open
E9 219	The safety temperature sensor has captured a temperature in excess of 105°C
E9 220	The contacts for the safety temperature sensor have shorted or the safety temperature sensor has detected a temperature higher than 130°c
E9 224	The contacts of the safety temperature sensor have been interrupted
E9 276	The temperature flow sensor has measured a temperature in excess of 95°c
E9 277	The safety temperature sensor has measured temperature in excess of 95°c
E9 285	The boiler return temperature sensor has measured a temperature higher than 95°c
E9 318	The flue gas temperature sensor contacts have been interrupted
EA 227	An insufficient ionisation current was measured following ignition of the burner
EA 229	The ionisation current detected by the system during the burning phase was insufficient
EA 234	The contacts of the gas valve have been interrupted
EA 261	The burner control unit is faulty
EA 269	The ignition device has been activated for too long
F0 238	The burner control unit KIM (boiler identification module) is faulty
F0 239	The burner control unit KIM (boiler identification module) has an error. Cabling might have poor contact breaks and pinching or the plug and wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit.
F0 242, F0 243. F0 244. F0 245, F0 246. F0 247, F0 248, F0 249, F0 250, F0 251, F0 252, F0 253, F0 255, F0 259, F0 263, F0 267, F0 272	The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit.
F0 278	The sensor test has failed – cabling and plug sensors need checking
F0 279	The burner control unit, or KIM, is faulty – control unit may need replacing
F0 280	The burner control unit is faulty
F0 287	The burner control unit, or KIM, has an error
F0 290	The burner control unit, or KIM, is faulty
F7 228	An ionisation current was measured before the burner started
F7 328	A brief power failure has occurred
FA 306	An ionisation current was measured after the burner went out
FD 231	The mains voltage was interrupted during an interlocking fault
EC 256	The burner control unit has an error
EH 258	The burner control unit is faulty – check the plug and wiring of the burner control unit.
H07	The current water pressure is too low, limiting the performance in heat mode as well as domestic hot water (DHW) mode
HrE	The boiler keeps resetting
rE	The boiler resets

Worcester Bosch CDI Highflow Combi Boiler Error Codes
A light on your boiler will flash to indicate that there is a fault. Depending on the type of fault, the light will flash in a different sequence.
There will be 4 quick flashes followed by a 5 second gap when the light is off and finally a series of longer flashes. The number of long flashes tells you which fault the boiler has.
Fault Description	System Behaviour
Light off	No boiler demand
Light on	Heating demand on boiler is OK
1 flash 5 seconds off	No ionisation detected after ignition
2 flashes 5 seconds off	Loss of ionisation signal during operation
3 flashes 5 seconds off	Gas valve error
4 flashes 5 seconds off	First safety timing error / ignition timing error
5 flashes 5 seconds off	Ionisation detected after burner stopped Gas valve EV2 leak test failed Gas valve EV1 leak test failed Ionisation current detected before burner start Gas valve error Ionisation sensor shorted
4 flashes 5 second gap 1 long flash	Sensor test failed
4 flashes, 5 second gap, 2 long flashes	Safety temperature too high
4 flashes, 5 second gap, 3 long flashes	Max safety thermostat activated
4 flashes, 5 second gap, 4 long flashes	Return temperature too high
4 flashes, 5 second gap, 5 long flashes	Flow temperature too high – supply sensor exceeded 110°c
1 long flash, 4 quick flashes, 5 second gap, 1 long flash, 4 quick flashes	Heating control module (HCM) defective
2 long flashes, 4 quick flashes, 5 second gap, 2 long flashes, 4 quick flashes	Fan running too fast Fan running too slow No airflow after defined period of time Fan not running
3 long flashes, 4 quick flashes, 5 second gap, 3 long flashes, 4 quick flashes	Mains voltage interrupted after locking error
4 long flashes, 4 quick flashes, 5 second gap, 4 long flash, 4 quick flashes	Internal control board faults
5 long flashes, 4 quick flashes, 5 second gap, 5 long flash, 4 quick flashes	All other miscellaneous faults – reset the boiler by turning the control knob anti-clockwise to the reset position
Worcester Bosch Greenstar Ri Boiler Error Codes
Fault Description	System Behaviour
No light	No power at control board
Light on	Appliance on but not operating during demand
Slow flash ( mostly off flashes on)	Ignition lockout
Slow flash ( mostly on flashes off)	Flue overheat or heat exchanger overheat
Fast flash	Volatile lockout sensor fan or code plug
2 pulses	Check service mode switch is in minimum position
5 pulses	Check service mode switch is in max position
Worcester Bosch Error Code EA 229 or D5
If you’re seeing the error code EA 229 or D5 on your Worcester Bosch boiler, this means that the condensate pipe is frozen. This happens due to the condensate pipe running outside, however this is an issue that you could fix yourself if you feel confident enough, you can find out how in our handy guide.

Glow Worm

Glow-worm Boiler Error Codes
Boiler Model	Fault Code	Cause of Problem
Betacom	Red LED on	Lockout – low water pressure (increase pressure to 1.5bar) and reset boiler
Betacom	Red LED flashing	Overheat – check both overheat stats
Betacom	Yellow LED flashing	Turn domestic hot water (DHW) control knob into temperature range and turn central heating (CH) temperature control knob into power (reset position) and wait for minimum of 30 seconds before turning into either summer or temperature position
Betacom	Yellow LED on	Flame present on the burner
Betacom	Green LED on	Boiler ready for operation
Betacom	Green LED off	No power to boiler – Check for 230volts into the appliance, check fuse on printed circuit board (PCB)
Betacom / Ultracom₂ cxi / sxi / 35	F00 / F10 / F71	Flow heating temperature sensor fault
Betacom / Ultracom₂ cxi / sxi / 35	F01 / F11	Return heating temperature sensor fault
Betacom / Ultracom₂ cxi / sxi / 35	F20	Overheating fault
Betacom / Ultracom₂ cxi / sxi / hxi / 35 / Flexicom cx / hx / sx	F9 / F22	Low water pressure (or ignition temperature rise too slow)
Betacom / Ultracom₂ cxi / sxi / 35	F26 / F77	Fault in gas valve
Betacom / Ultracom₂ cxi / sxi / 35 / CI / hxi / Xtramax HE	F27 / F16	Flame detection fault
All Boilers	F28 / F1 / F4	Ignition fault (flame detection)
Betacom / Ultracom₂ cxi / sxi / 35	F29	Loss of flame during operation
Betacom / Ultracom₂ cxi / sxi / 35	F32	Incorrect air pressure
Betacom / Ultracom₂ cxi / sxi / 35	F49	EBUS voltage fault
Betacom / Ultracom₂ cxi / sxi / 35	F61 / F62 / F63 / F64 / F65 / F67	Fault in the main board
Betacom / Ultracom₂ cxi / sxi / 35	F68	Fluctuation of flame signal
Betacom / Ultracom₂ cxi / sxi / 35	F70	User interface incompatible with the main board
Betacom / Ultracom₂ cxi / sxi / 35	F72 / F84	Permanent temperature difference between flow and return heating sensors
Betacom / Ultracom₂ cxi / sxi / 35	F73 / F74	Heating circuit pressure sensor fault
Betacom / Ultracom₂ cxi / sxi / 35	F76	Thermal fuse fault
Betacom / Ultracom₂ cxi / sxi / 35	F83	Thermal fuse fault
Betacom / Ultracom₂ cxi / sxi / 35	F85	Flow and Return heating sensor fault
Betacom / Ultracom₂ cxi / sxi / 35	F86	Underfloor heating contact fault
All Boilers	ERR / F12 / F18	User interface fault
Betacom c	Temperature 30 flashing	Fault on central heating (CH) thermistor
Betacom c	Temperature 40 flashing	Fault on DHW thermistor
Betacom c	Temperature 50 flashing	Fault on outside sensor
Betacom c	Temperature 60 flashing	Low system pressure
Betacom c	Temperature 70 flashing	Fault on APS
Betacom c	Temperature 80 flashing	Overheat open circuit
Betacom c	Temperature 90 flashing	Flame or gas failure
Compact e / s	No DHW	Check dhw microswitch / Check external controls, Please test for 230V on switch live contact
Compact e / s	No C/H	Check dhw microswitch if dhw demand led is lit / Check external controls, Please test for 230V on switch live contact
Compact e / s	No C/H but boiler is firing	Check diverter motor and cartridge / Check external controls, Please test for 230V on switch live contact
Compact e / s	Boiler locks out within 10 seconds	Check pump proving switch, air pressure switch and overheat state / Check pump proving switch, air pressure switch and overheat stat
Compact e / s	Poor burner pressure	Check burner pressure/ignition adjustment pots on PCB
Ci Range (plus) / Si range	F2	Fan/APS
All Boilers	F5	Overheat Fault
All Boilers	F6	Central heating flow thermistor
All Boilers	F7	Domestic hot water thermistor
All Boilers	F8	Tank thermistor fault
sxi / si / ci (plus) range / Xtramax HE	F9	Water pressure sensor fault (please contact GW technical department for further information)
All boilers	F10	Central return flow thermistor
All boilers	F11	Main board connection fault
Ci (plus) / cxi / hxi / si / sxi range	F12	Connection fault between main printed circuit board (PCB) and display PCB
Ci (plus) / cxi / hxi / si / sxi range	F13	Main PCB connection fault
Ci (plus) / cxi / hxi / si / sxi range	F14	Central heating flow temperature > 95 degrees
Ci (plus) / cxi / si / sxi range	F15	Gas valve stepper motor fault
Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE	F17	Power supply is less than 170v
Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE	F19	Central heating thermistor unplugged
Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE	F20	Software incompatibility
cxi / hxi / sxi range / Flexicom cx	F24	Central heating return temperature > 90 degrees
cxi / hxi / sxi / Xtrafast 96/120 / Xtrafast 96/120E1	F25 / F26 / F11	Poor circulation
ci range	F3	Air fault
ci range	F3	Air fault
cxi / sxi / hxi range/ Xtramax HE	F2 / F3	Fan
cxi / sxi range / Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi / Ultrapower sxi	F3	Fan unable to reach ignition speed
Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi	F9	Water pressure sensor fault, blocked flow filter or pump fault
Flexicom cx / hx / sx	F11	Flow and or return thermistor fault
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE	F13	PCB memory or sensing fault
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE	F14	Gas valve control defective
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE	F15	E-bus voltage failure
All boilers	F25 / F23	Circulation fault
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi	F43	Generic error
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi	F70	Software incompatible
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi	F73	Unable to see pump activate
Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi	F77	Condensate pump error (optional)
hxi range	F9	Earlier models only (please contact GW technical department for further information)
hxi range	F9	Earlier models only (please contact GW technical department for further information)
Ultracom₂ 35 Store	F02 / F12	Hot water temperature sensor fault
Ultracom₂ 35 Store	F03 / F13 / F79	Storage tank temperature sensor fault
Ultracom₂ 35 Store	F81	Overheating of hot water circuit
All Ultracom	No display or Er	loose connection X51
Xtramax HE Range	F24	Cental heating return temperature > 90 degrees
Xtramax HE Range	F25	Maximum temperature rise slope
Xtramax HE Range	F26	Maximum delta temperature
Xtrafast 96/120 Range	F00	No fault/td>
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F00	No fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F02	Air flow fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F05	Overheating
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F06	Central heating thermistor/wiring fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F08	Storage vessel thermistor/wiring fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F09	System pressure sensor fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F10	Fan fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F13	Main printed circuit board (PCB) fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F14	Central heating flow temperature > 97 degrees
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F15	Gas mechanism fault
Xtrafast 96/120 Range / Xtrafast 96/120E1 Range	F20	Communication fault
Glow-worm Energy Boiler Range Error Codes
Fault Code	Cause of Problem
F.00	Flow temperature sensor
F.00	Flow temperature sensor
F.10	Flow temperature sensor short circuit
F.11	Flow temperature sensor short circuit
F.12 and F.91	Cylinder temperature sensor short circuit
F.13	Domestic hot water cylinder temperature sensor short circuit
F.20	Safety switch-off – overheating temperature reached
F.22	Safety switch-off – low water pressure in the boiler
F.23	Safety switch-off – temperature difference too great (NTC1/NTC2)
F.24	Safety switch-off – temperature rise too fast
F.25	Safety switch-off – flue gas temperature too high
F.27	Safety switch-off – fault in flame detection
F.28	Ignition unsuccessful when starting up
F.29	Flame loss
F.32	Fan frost protection function active – fan speed outside the tolerance values
F.33	Fan frost protection function active – air pressure switch fault
FA9	eBUS fault – voltage too low
F.61	Gas valve control system fault
F.82	Gas valve switch-off control fault
F.83	EEPROM fault – electronics defective
F.64	Electronics/sensor/analogue-to-digital converter fault
F.85	Electronics temperature too high
F.67	Value sent back by ASIC is incorrect (flame signal)
F.88	Unstable flame (analogue input), underfloor heating contact or gas valve fault
F.70	Invalid product code (DSN)
F.71	Flow/return temperature sensor
F.72	Deviation in the water pressure sensor/return temperature sensor
F.73	Water pressure sensor not connected or has short-circuited
F.74	Electrical problem in the water pressure sensor
F.75	Pressure sensor fault
F.78	The safety cut-out in the primary heat exchanger is defective
F.77	Fault: Condensate or smoke
F.78	Interruption to domestic hot water (DHW) outlet sensor at external controller
F.83	Burner temperature sensor fault
F.84	Flow/return temperature sensor fault
F.85	Temperature sensor fault
F.87	Electrodes fault
F.89	Pump fault
Connection	No communication between the printed circuit board (PCB) and the user interface
Glow-worm Error Codes F1, F4, F28 or F29
If you are seeing the error codes F1, F4 F28 or F29 on your boiler there’s an issue with your condensate pipe. This error appears when your pipe is frozen, which can happen during the cold months as it runs outdoors. You can fix this issue yourself if you feel confident enough, otherwise call an engineer, by thawing out the pipe which you can find out how to do with our handy guide to thawing a condensate pipe.

Vaillant

Vaillant Turbomax Plus 824/828E
Fault Code	Possible Cause	Meaning
F.00	NTC FAULTS	This means that your Flow NTC (Negative Temperature Coefficient Thermostat) cable is either defective or broken and needs to be replaced
F.01	NTC FAULTS (feed temperature sensor) – faulty connection and open circuit.	This means that your Flow NTC (Negative Temperature Coefficient Thermostat) cable is either defective or broken and needs to be replaced
F.10	NTC FAULTS (feed temperature sensor) – short circuit	—
F.11
F.13	NTC FAULTS (feed temperature sensor) – short circuit	—
F.20	NTC FAULTS (feed temperature sensor)	Your boiler has exceeded the maximum temperature and needs to be allowed to cool down
F.22	DRY FIRE, LOW WATER IN SYSTEM/OVERHEAT	This means that there’s either no water in your system, you have a defective pump or the pump lead is defective
F.24	LOW WATER, OR PUMP FAILURE/BLOCKAGE	Your pump could be obstructed, running at low capacity, or there could be air trapped in your appliance. Additionally, the pressure in your system might be too low.
F.28	NO IGNITION/IGNITION PROBLEM	This means there’s either insufficient gas in the system, a defective electrode, ignition lead or electronic ignitor
F.29	FLAME EXTINGUISHED. FAN/FLUE PROBLEM/GAS	Your flame, or pilot light has gone out. Check your flue duct or gas supply to see if there is a problem there.
F.60	GAS VALVE CONTROL – DEFECTIVE	Your cable loom which connects to your gas valve might have short circuited. Alternatively, you could have a defective gas valve assembly or electronic control system.
F.61	GAS VALVE CONTROL – DEFECTIVE	Your cable loom which connects to your gas valve may have short circuited. Alternatively, you could have a defective gas valve assembly or electronic control system.
F.62	DEFECTIVE GAS VALVE CLOSURE MECHANISM	Your boiler has exceeded the maximum temperature and needs to be allowed to cool down
F.63	EEPROM (Electrically Erasable Programmable Read-Only Memory) ERROR	This is an electronic fault within your system.
F.64	ELECTRONIC SYSTEM/SENSOR FAULT	Your flow or back flow NTC has suffered a short circuit, or an electronic fault
F.65	ELECTRONIC SYSTEM TEMPERATURE TOO HIGH	This can happen because of an external heat source or an electrical fault
F.67	ELECTRONIC FAULT IN FLAME SYSTEM	—

Vaillant EcoMax Pro 18/28E
Fault Code	Possible Cause
F.1	Lack of gas, a fault with the ignition or flue or you may need to adjust the gas valve or replace a defective electrode lead.
F.4	Ignition fault.
F.5	The system has suffered a fault due to overheating.
F.6	Your flow NTC has developed a fault.
F.17	Check the polarity of your system.
F.24	Pump-related faults – the pump could have failed, it may have over run or there could be an issue with the airlock



Vaillant Ecomax Pro 828E
Fault Code	Possible Cause
F.00, .04, .05, .10, .14, .15	All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
F.21	The pilot flame has failed.
F.22	There is insufficient water in your system.
F.11	A blockage in the appliance is preventing the system from flowing as it should.
F.12	A blockage in the appliance is affecting the system’s pressure.
F.13	The appliance is blocked because of a water deficiency.

Vaillant EcoTEC 65kW Error Codes
Fault Code	Possible Cause
S.O	Heating issue, no heat demand
S.1	Fan start-up error
S.2	Pump flow error
S.3	Heating mode error – ignition problem
S.4	Heat mode – burner on error
S.6	Heating mode – fan overrun error
S.7	Heating mode – pump overrun error
S.8	Heating remaining cut off for XX amount of time
S.31	No heat demand summer operating mode
S.34	Heating mode frost protection error
S.20	Hot water requirement error
S.22	Hot water handling pump flow error
S.24	Hot water operation burner is on
S.85	Service message quantity of circulation water

Vaillant EcoTEC Pro / EcoTEC Plus Error Codes
Fault Code	Possible Cause
F.00 / F.0	Flow temperature sensor interruption
F.01 / F.1	Return temperature sensor interruption
F.10	Flow NTC short circuit
F.11	Return NTC short circuit
F.20	Safety switch off temperature limiter
F.22	Safety switch off low water pressure
F.23	Safety switch off temperature difference too great
F.24	Safety switch off temperature is rising to fast
F.25	Safety switch off flue gas temperature too high
F.26	Error with gas valve – possible no function
F.27	Safety switch off flame simulation
F.28	Failure during start up – ignition unsuccessful to start
F.29	Failure during operation – re-ignition unsuccessful
F.32	Fan error
F.49	eBUS error – possible short circuit
F.61	Error with gas valve regulation
F.62	Error with gas valve – switch off delay
F.63	EEPROM error
F.64	Electronics / NTC error
F.65	Electronic temperature error could be overheating due to external influences
F.67	Electronics flame signal error
F.68	Unstable flame signal error air in gas
F.70	Invalid device specific number (DSN)
F.71	Flow NTC error – flow temperature sensor signal constant value
F.72	Flow return NTC error – temperature difference too great
F.73	Water pressure sensor signal in the wrong range, it is too low
F.74	Water pressure sensor signal outside correct range, the sensor signal is too high
F.75	Error with pressure – no pressure change detection when starting the pump
F.76	Overheating protection on – primary heat exchanger has responded
F.77	Flue non return flap condensate pump error
F.78	Interruption to DHW outlet sensor at external controller
F.83	Flow and or return temperature sensor error
F.84	Error with flow/return temperature sensor temperature changing error
F.85	Error with flow and return temperature, sensor incorrectly fitted
CONNECTION	No communication with the PCB

Vaillant EcoTEC Pro / EcoTEC Plus Error Codes
Fault Code	Possible Cause
S.00	Heating mode error – no heat demand
S.01	Heating mode fan start-up
S.02	Heating mode error – water pump running
S.03	Heating mode – ignition sequence error
S.04	Heating mode – burner ignited
S.06	Heating mode – fan overrun error
S.07	Heating mode – pump overrun error
S.08	Heating remaining cut off time xx minutes
S.10	Hot water demand via impeller sensor
S.11	DHW mode fan start up error
S13	DHW mode ignition error
S.14	Hot water demand via fan sensor error
S.15	DHW mode pump and fan overrun
S.16	DHW mode – fan overrun error
S.17	DHW mode – pump overrun error
S.20	DHW mode – burner on error
S.21	DHW mode – fan start up error
S.22	DHW demand – error pump running
S.23	DHW ignition error
S.24	DHW mode – burner error
S.25	DHW mode – pump or fan overrun error
S.26	DHW mode – fan overrun
S.27	DHW mode – pump overrun
S.28	Hot water burner anti-cycling time
S.30	Room thermostat is blocking heating mode
S.31	No heat demand boiler in summer operating mode
S.32	Waiting period because of fan speed deviation
S.34	Heating mode frost protection error
S.39	Burner off contact has been triggered this could be because of contact thermostat or condensate pump
S.40	Comfort safety mode active
S.41	Water pressure > 2.8 bar
S.42	Flue non return flap return signal blocks burner operation
S.46	Comfort safety mode flame loss at minimum load
S.53	Boiler is in waiting period of modulation f block function due to water shortage
S.54	Boiler is in waiting period of operation, blocking function as a result
S.57	Waiting period comfort safety mode
S.58	Modulation limitation due to noise / wind error
S.61	Gas family check unsuccessful


Vaillant EcoTEC Plus Regular Gas Boiler Error Codes
Fault Code	Possible Cause
S.20	Warnstar demand
S.21	Fan running
S.22	Pump running
S.23	Ignition sequence
S.24	Burner ignited
S.25	Fan and water pump running
S.26	Fan overrun
S.27	Pump overrun
S.28	Anti-cycling mode
S.30	No heating demand from external controls
S.31	Central heating thermostat knob turned off
S.32	Heat exchanger antifreeze active as fan speed variation is too high
S.34	Anti-frost mode is active
S.36	Not heating demand form low voltage
S.41	Water pressure greater than 2.9 bar
S.42	Response from accessory module or defective condensate pump is blocking burner operation
S.53	Appliance is within the waiting period of the block operation function due to water shortage
S.54	Appliance is within the waiting period of the block operation due to water shortage
S.96	Return sensor error
S.98	Flow return sensor check is running demand is block
D.0	Heating part load error
D.1	Water pump overrun – time for heat mode
D.2	Max burner anti-cycling period at 20c flow temperature
D.3	Hot water flow temperature reading
D.4	Current temperature for warm stat sensor
D.7	Warm start temperature target value
D.8	External controls heat demand
D.9	Flow target temperature from external analogue regulator terminal
D.10	Status internal heating pump error
D,11	Status external heating pump error
D.12	Cylinder charging pump via accessory module
D.13	Hot water circulation pump
D.22	Hot water demand
D.23	Summer/Winter function
D.25	Hot water activation via ebus control
D.30	Control signal for both gas valves
D.33	Fan speed target value
D.34	Fan speed actual value
D.36	Hot water flow sensor
D.40	Flow temperature target value
D.41	Return temperature actual value
D.44	Digitised ionisation potential error
D.47	Outside temperature with weather compensator – Vaillant controller only
D.76	Remaining burner anti-cycling time in min
D.90	Digital regulator status
D.91	DCF status with connected external probe
D.97	Activation of the second diagnostic level
D.17	Heating glow return regulation
D.18	Pump mode return
D.19	Operating modes of the two speed heating pump
D.20	Maximum set value for target cylinder
D.27	Switching accessory relay 1
D.28	Switching accessory relay 2
D.50	Offset for minimum speed
D.51	Offset for maximum speed
D.58	Activation of solar reheating
D.60	Number of safety temperature cut off
D.61	Number of unsuccessful lockouts
D.64	Average ignition times
D.65	Maximum ignition time
D.68	Unsuccessful ignitions in the first attempt
D.69	Unsuccessful ignition for the second time
D.70	Set diverter valve position
D.71	Maximum setting of heater control knob
D.72	Pump overrun time after warm start
D.73	Off set for warm start target value
D.75	Maximum charging time for a storage without own controller
D.77	Limitation of cylinder charging in output in kW
D.78	Limitation of cylinder charging temperature in c
D.80	Operating hours heating
D.81	Operating hours hot water generation
D.82	Burner start up in heating mode
D.83	Burner start up in hot water mode
D.84	Maintenance indicator – number of hours until the next maintenance
D.93	DSN appliance variant setting
D.96	Factory setting

Vaillant EcoTEC Plus Gas Boiler Error Codes
Fault Code	Possible Cause
P.00	The heating circuit and hot water circuit are purged
P.01	Maximum load test program error
P.02	Minimum load test program
P.06	Filling mode test program

Vaillant EcoTEC Gas Boiler Error Codes
Fault Code	Possible Cause
D.0	Heating part load error
D.1	Water pump overrun – time for heat mode
D.2	Max burner anti-cycling period at 20c flow temperature
D.3	Hot water flow temperature reading
D.4	Current temperature for warm stat sensor
D.5	Set value of flow temperature or target value of return
D.7	Warm start temperature target value
D.8	External controls heat demand
D.9	Flow target temperature from external analogue regulator terminal
D.10	Status internal heating pump error
D,11	Status external heating pump error
D.12	Cylinder charging pump via accessory module
D.13	Hot water circulation pump
D.15	Pump speed actual value
D.22	Hot water demand
D.23	Summer/Winter function
D.24	Not relevant
D.25	Hot water activation via eBus control
D.30	Control signal for both gas valves
D.33	Fan speed target value
D.34	Fan speed actual value
D.35	Not relevant
D.40	Flow temperature target value
D.41	Return temperature actual value
D.44	Digitised ionisation – potential error
D.47	Outside temperature with weather compensator – Vaillant controller only
D.76	Remaining burner anti-cycling time in min
D.90	Digital regulator status
D.91	DCF status with connected external probe
D.97	Activation of the second diagnostic level
D.98	Telephone a heating engineer
D.14	Pump speed target value
D.17	Heating flow return regulation
D.18	Pump operating mode
D.20	Maximum set value for target cylinder
D.26	Additional relay control ecoTec
D.27	Switching accessory relay 1
D.28	Switching accessory relay 2
D.50	Offset for minimum speed
D.51	Offset for maximum speed
D.60	Number of safety temperature cut offs
D.61	Number of unsuccessful lockouts
D.64	Average ignition times
D.65	Maximum ignition time
D.67	Remaining burner anti-cycling time
D.68	Unsuccessful ignitions in the first attempt
D.69	Unsuccessful ignition for the second time
D.70	Set diverter valve position
D.71	Maximum setting of heater control knob
D.72	Pump overrun time after warm start
D.75	Maximum charging time for a storage without own controller
D.77	Limitation of cylinder charging in output in kW
D.78	Limitation of cylinder charging temperature in celsius
D.80	Operating hours heating
D.81	Operating hours hot water generation
D.82	Burner start up in heating mode
D.83	Burner start up in hot water mode
D.84	Maintenance indicator – number of hours until the next maintenance
D.93	DSN appliance variant setting
D.96	Factory setting

Vaillant Error Codes F28 and F29

If your Vaillant boiler is showing either error code F28 or F29 then the condensate pipe has frozen and needs to be thawed. This issue can occur during the colder months as the pipe runs outside but can be resolved fairly easily without the need for an engineer as the pipe just needs to be thawed out. Find out everything you need to know by checking our handy guide to thawing a frozen condensate pipe.

Zanussi

Zanussi Boiler Error Codes
Fault Code	System Behaviour
C0	Boiler chip card (BCC) activation fault
C2	Boiler chip card (BCC) fault
F1	Low water pressure
F2	Flame loss
F3	Fan fault
F4	Flow thermistor
F5	Return thermistor
F6	Outside sensor failure
F7	Low mains voltage
F9	Un-configured printed circuit board (PCB)
L1	Flow temperature overheat or no water flow
L2	Flame loss
L5	5 boiler resets in 15 minutes
L6	False flame lockout

Ideal

Ideal Boiler Error Codes
Fault Code	System Behaviour
C0	Boiler chip card (BCC) activation fault
C2	Boiler chip card (BCC) fault
F1	Low water pressure
F2	Flame loss
F3	Fan fault
F4	Flow thermistor fault
F5	Return thermistor fault
F6	Outside sensor failure
F7	Low mains voltage
F9	Un-configured printed circuit board (PCB)
L1	Flow temperature overheat or no water flow
L2	Flame loss
L5	5 boiler resets in 15 minutes
L6	False flame lockout
Fault Code	System Behaviour
0	The boiler is in standby mode awaiting either a central heating call or hot water demand
C	The boiler has a call for central heating but the appliance has reached the desired temperature set on the boiler
D	The boiler has a call for hot water but the appliance has reached the desired temperature set on the boiler
C	The boiler is operating in central heating mode
d	The boiler is operating in hot water mode
F	The boiler is operating in frost mode
Ideal Logic Max System / Logic Plus System Boiler Error Codes
Fault Description	System Behaviour
L1	Flow temperature overheat lockout or no water flow lockout
L2	Ignition lockout
LC	Turn power off and on
L6	False flame lockout
F1	Low water pressure
F2, FN or LN	Flame loss
F3	Fan fault
L4 or F4	Control / no flow thermistor fault
L5 or F5	Return thermistor fault
F6	Outside sensor fault
F7	Low mains voltage. Contact electricity provider.
F9, L9, F8 or L8	Printed circuit board (PCB) un-configured or fault
FU	Diff greater than 50c check isolation valves are open
No central heating
No hot water
No display
Ideal Logic Max / Logic Plus Regular Boiler Error Codes
Fault Description	System Behaviour
L1	Flow temperature overheat lockout or no water flow lockout
L2	Ignition lockout
LC	5 restarts within 15 minutes
L6	False flame lockout
FA	Flow return reversed
FD	No water flow
F2 or FN or LN	Flame loss
F3	Fan fault
L4 or F4	Control / no flow thermistor fault
L5 or F5	Return thermistor fault
F6	Outside sensor fault
F7	Low mains voltage Contact electricity provider
F9, L9, F8 or L8	Printed circuit board (PCB) un-configured or fault
FU	Diff greater than 50c check isolation valves are open

Ideal Logic Max Plus Combi Boiler Error Codes
Fault Description	System Behaviour
Overheat lockout	Bleed radiators, refill system to 1.0 bar, check that radiator and boiler valves are open and reset boiler. If fault continues book an engineer.
Ignition lockout	Check gas appliances work and restart boiler.
Too many restarts	5 starts within 15 minutes. Turn power on and off.
Flame on before gas on	False flame lockout.
Water pressure	With boiler off and system cold fill system to 1.0 bar and bleed radiators if fault continues contact an installer.
Ideal Vogue Boiler Error Codes
Fault Description	System Behaviour
Too many resets	5 restarts within 15 minutes
Flame on before gas valve on	Flame on before gas valve is on
Flow thermistor fault	Flow thermistor error
Low mains voltage	Less than 185v to boiler then check voltage at boiler mains in if mains voltage is okay pump needs replacing
Low water pressure	Low water pressure
Flow return reversed	Check if the flow thermistor is correctly clipped to pipe. If not, replace flow thermistor.
Printed circuit board (PCB) recently replaced	Reset boiler
Pump rotor blocked	Unblock pump
Flow temperature set point cannot be increased to 80c	Check flow and return thermistors securely clamped to pipes check flow and return thermistor

Ideal Boiler Error Descriptions
Fault Description	Cause
Thermal fuse lockout	Reset the boiler
Too many boiler resets	5 resets within 15 minutes. Turn power off and on.
Printed circuit board (PCB) replaced incorrectly	Ensure the boiler chip card (BCC) is fitted correctly.
Low mains voltage	Less than 160V to boiler. Contact electricity provider.
Low water pressure	Increase system pressure to 1.5 bar
Flow/Return reversed	Check if flow thermistor is correctly clipped to pipe. Replace flow thermistor.
Printed circuit board (PCB) replaced	Reset the boiler
No connection to primary printed circuit board (PCB)	Unblock pump
Pump rotor blocked	No connection to primary printed circuit board (PCB)
Flow temperature set point cannot be increased to 80ºC	Ensure flow temperature is not limited within installer mode
Pump runs during the night	Ensure system frost protection temperature set point isn’t set too high
Has the printed circuit board (PCB) just been replaced?	Reset the boiler
Are the boiler, central heating and hot water systems filled with water? Are all isolation valves and radiator valves open?	Fill and vent the system and open all isolation valves, then reset the boiler
Is the Flow/Return differential across the boiler in excess of 30c	Check the flow and return thermistors
Check that the pump is rotating freely.	Replace the pump, then reset the boiler
If the boiler is reset, does it ignite for a short time and then extinguish?	Check the detection electrode and associated harness for continuity, visual condition and position. Check if the condensate pipe is blocked.
Is the gas pressure available at the boiler > 18mBar	Check gas supply and rectify fault
Is 215Vdc available at the gas valve during ignition?	Check wiring from gas valve to printed circuit board (PCB) and replace if necessary, otherwise replace the main PCB
Unplug the gas valve – is the resistance between the pins between 1kW and 10kW?	Replace gas valve

Baxi

Baxi Platinum Error Codes
Fault Code	Possible Cause
E20	Central heating NTC error
E28	Error with the NTC flue. Possible air pressure switch error. Blocked flue or condensate or wing fault
E50	Hot water NTC error
E110	Thermostat operated safety
E119	Water pressure switch error – Not operated.
E125	Primary circuit error circulation fault
E130	FLue NTC Operation error
E133	Gas supply Error or flame failure
E160	Fan Error / Fan Wiring Error
E193	Pre-circulation error
Baxi EcoBlue Error Codes
Fault Code	Possible Cause
110	Overheated – try bleeding your radiators
117	Water pressure too high
118	Water pressure too low
125	Water circulation fault
133	Safety time to establish flame exceeded
E10	Outdoor sensor error
E20	Central heating thermistor sensor fault
E28	Flue thermistor fault
E54	Domestic hot water (DHW) flow sensor fault
E78	Water pressure sensor fault
E100	Internal clock time error on printed circuit board (PCB)
E109	Poor circulation
110	Overheat – try bleeding your radiators
111	Maximum limit of flow temperature
117	Water pressure too high
118	Water pressure too low
119	System pressure too low
125	Water circulation fault
127	Legionella (cause of Legionnaires’ disease) protection temperature not reached
128	Loss of flame during operation
133	Safety time to establish flame exceeded
153	Forced reset unit unlocked
160	Fan fault
162	Air pressure switch error
164	Pressure Sensor Error (UK) – Heating flow switch error (Ireland)
166	Air pressure switch fault
270	Dry fire
432	Earth connector error
433	Heat exchanger temperature exceeded (greater than 95 degrees)
EcoBlue Advance / Ecoblue Regular Gas Boiler Flashing Light Error Codes
Fault Code	Possible Cause
1 green flash	Boiler temperature reached. No action required.
3 green flashes	Temporary flame loss. Boiler will self reset, if fault continues you will see 3 red flashes.
4 green flashes	Communication error between printed circuit board (PCB) and control. Temporary error, will self reset.
5 green flashes	Parameter error on printed circuit board (PCB). Temporary error, will self reset
6 green flashes	Miscellaneous error. Temporary error, will self reset.
1 red flash	Sensor error, temperature fault or flow fault.
2 red flashes	Boiler overheat tripped
3 red flashes	Ignition fault. Boiler has attempted to light 5 times and failed.
4 red flashes	Fan fault
5 red flashes	Parameter storage unit (PSU) error.
6 red flashes	Miscellaneous error.
Baxi Duo-tec/Megaflo Error Codes
Fault Code	Possible Cause
E10	Outdoor sensor fault
E20	Central heating thermistor sensor error
E28	Flue thermistor error
E110	Boiler overheat error
E119	Low water pressure error
E125	Primary water circulation error
E131	Flue overheat lockout error
E133	Ignition error
E160 / E161	Fan error
E164	Pressure sensor fault
E167	Printed circuit board (PCB) error
E168	Printed circuit board (PCB) lockout error
E193	Circulation error
Baxi 200 / 400 Combi Gas Boiler Error Codes
Fault Code	Possible Cause
H.01 – .00	Loss of communication between gas valve and boiler board. Possible fault in air/gas unit or loose connection to gas valve.
H.01 – .05	Difference between the flow and return temperature is too high, sensor error or insufficient circulation.
H.01 – .08	Sensor fault, flow temperature increasing too fast in heating mode or insufficient circulation.
H.01 – .14	Maximum flow temperature value exceeded or insufficient circulation – temporary fault.
H.01 – .18	No water circulation, insufficient circulation or sensor error.
H.01 – .21	Temporary error – flow temperature increasing too fast in domestic hot water (DHW) mode, insufficient circulation or sensor error.
H.02 – .02	Temporary error – no input of parameters C1/C2. Printed circuit board (PCB) not configured.
H.02 – .03	Temporary error- incorrect configuration settings C1/C2.
H.02 – .04	Temporary error- parameter fault. Incorrect parameters.
H.02 – .06	Temporary error caused by system water pressure, water leak on boiler, water leak on system.
H.03 -.00	Temporary error with communication, negative temperature coefficient thermostat (NTC) or flue sensor. Sensor could also be unconnected or have a bad connection.
H.03 – .01	Communication error with the printed circuit board (PCB)
H.03 – .02	Flame error – no flame during operation.
E.00 – .04	Return temperature sensor open-circuit. Sensor not or badly connected.
E.00 – .05	Return temperature sensor short-circuit. Sensor not connected or badly connected.
E.01 – .02	Temperature measured by return sensor greater than flow sensor.
E.01 – .04	Loss of flame detected 5 times in 24 hours (with burner on).
E.01 – .11	Incorrect fan speed – external draught over the boiler or defective gas/air unit.
E.01 – .12	Requires reset – temperature measured by return sensor greater than flow temperature.
E.01 – .17	Reset the boiler – no circulation, sensor fault either not connected or has a bad connection.
E.01 – .20	Maximum flue gas temperature reached. No circulation or sensor fault.
E.02 – .00	Reset button has been pressed.
E.02 – .07	No or low system water pressure. system pressure less than 0.5bar
E.02 – .16	Permanent fault caused by channel service unit (CSU) time-out or printed circuit board (PCB) damage.
E.02 – .17	Loss of communication between gas valve and boiler printed circuit board (PCB) or fault in air/gas unit.
E.02 – .19	Jumper 1 changed – check position of jumper 1.
E.02 – .20	Jumper 2 changed – check position of jumper 2.
E.02 – .21	Jumper 3 changed – check position of jumper 3.
E.02 – .47	Wiring to external device error.
E.02 – .48	Configuration to external device unsuccessful – check pairing to external device.
E.04 – .00	Gas valve error – gas valve not detected.
E.04 – .01	Flow temperature sensor short-circuited. Sensor not or badly connected, bad connection or sensor fault.
E.04 – .02	Permanent fault. Flow temperature sensor open-circuited, sensor not or badly connected, bad connection or sensor fault.
E.04 – .03	Permanent fault. Critical flow temperature reached, non-existent or insufficient circulation.
E.04 – .04	Permanent fault. Flue temperature sensor short-circuited, sensor not or badly connected, bad connection or sensor fault.
E.04 – .05	Permanent fault. Flue temperature sensor short-circuited, sensor not or badly connected, bad connection or sensor fault.
E.04 – .06	Permanent fault. Critical flue gas temperature value reached, no circulation or sensor fault.
E.04 – .08	Permanent fault. Maximum safe temperature value reached, safety thermostat open-circuited, no circulation, sensor not or badly connected, bad connection or sensor fault.
E.04 – .10	Failure to light (could be gas supply issue).
E.04 – .12	Permanent fault. False flame signal, short-term fluctuation of the mains, ionisation current present even though there is no flame, the burner remains very hot (CO2 too high) or defective gas/air unit.
E.04 – .13	Permanent fault. Fan rotor blocked, fan seized or wiring to fan damaged.
E.04 – .17	Permanent fault. Problem with gas valve or defective gas/air unit.
Baxi 600 Combi Gas Boiler Error Codes
Fault Code	Possible Cause
E09	Gas valve connection cable.
E10	External probe fault.
E12	Differential water flow switch fault (still open).
E13	Differential water flow switch fault (still closed).
E15	Gas valve command fault.
E20	Central heating negative temperature coefficient (NTC) thermostat fault.
E28	Flue negative temperature coefficient (NTC) thermostat fault.
E40	Central heating return negative temperature coefficient (NTC) thermostat fault.
E50	Domestic hot water (DHW) negative temperature coefficient (NTC) thermostat sensor fault (tank boiler) (s.c.) or DHW NTC sensor fault (tank boiler) (o.c.).
E83/E84/E85/E86/E87	No communication.
E109	Pre-circulation fault.
E110	Boiler max temperature exceeded for gradient (probable pump jammed or air in the circuit Boiler max temperature exceeded for over temperature (probable pump jammed or air in the circuit Safety thermostat sensor tripped.
E118	Primary system water pressure too low (< 0.5 bar).
E125	Circulation fault (primary).
E128	Frequent flame failure (12 times).
E129	Safety error for frequently loss of flame with max correction during the ignition during Calibration Function.
E130	Flue thermostat sensor tripped (lockout).
E133	Failure to light (could be a gas supply issue).
E134	Elapsed time gas valve open without gas (short request in a short period)
E135	Interruption of gas supply (internal error).
E154	Flow/return sensor temperature test.
E160	Fan or fan wiring fault.
E163	Domestic hot water (DHW) negative temperature coefficient (NTC) thermostat sensor fault (s.c.) or DHW NTC sensor fault (o.c.).
E270	Circulation fault (dry fire).
E317	Wrong power supply electrical frequency (Hz).
E321	Hot water negative temperature coefficient (NTC) fault.
E384	False flame.
E385	Under voltage.
E430	Water pressure temporary test.
E430 + Flame ‘crossed’	Water pressure test failed.
Baxi MainEco Error Codes
Fault Code	Possible Cause
1 Green Flash	Boiler temperature reached – no action required
3 Green Flashes	Temporary flame loss – this is a temporary error, the system should reset on its own
4 Green Flashes	Communication error between printed circuit board (PCB) and Control – this is a temporary error, the system should reset on its own
5 Green Flashes	Parameter error on parameter storage unit (PSU) or printed circuit board (PCB) – this is a temporary error, the system should reset on its own.
6 Green Flashes	Miscellaneous error
1 Red Flash	Sensor error, sensor fault, temperature fault or flow fault – this is a temporary error, the system should reset on it’s own.
2 Red Flashes	Boiler overheat tripped
3 Red Flashes	Ignition fault. Boiler has attempted to light 5 times and failed
4 Red Flashes	Fan Fault
5 Red Flashes	Parameter storage unit (PSU) error
6 Red Flashes	Miscellaneous


Baxi Avanta Range Error Codes
Fault Code	Possible Cause
E0	Temperature sensor fault
E1	Overheated – try bleeding your radiators
E2	Poor circulation – try bleeding your radiators
E3	Printed circuit board (PCB) fault
E4	Ignition failure – try bleeding your radiators
E10	Poor/No circulation
E12	Printed circuit board (PCB) Fault
E13	Heat exchanger thermal fuse tripped
E83 / 84 / 85 / 86 / 87	Fan fault normally E8
Baxi GA Range Error Codes
Fault Code	Possible Cause
E53	Poor combustion – flue terminal may be blocked
E110	Overheated – try bleeding your radiators
E117	System water pressure high – try bleeding water from your radiators
E118	System water pressure low
E125	Overheat – try bleeding your radiators
E133	Gas supply fault
E4	Ignition failure
E09	Gas valve wiring fault
E10	Outdoor sensor error
E15	Gas valve connection fault
E20	Central heating thermistor sensor fault
E28	Flue thermistor fault
E40	Central heating return thermistor fault
E53	Flue obstruction
E55	Calibration required
E78	Water pressure sensor fault
E92	Combustion test alarm during auto-setting
E109	Poor circulation
E110	Boiler overheat tripped
E117	System pressure high (>2.9 Bar)
E118	System pressure low(< 0.5bar)
E125	Primary water circulation fault
E128	Loss of flame during operation
E129	Loss of flame during calibration
E133	Ignition fault
E135	Internal error
E154	Primary flow fault
E160	Fan fault
E270	Dry fire
E317	Wrong power supply (Hz)
E321	Not water thermistor fault
E384	Flame detected when gas valve off
E385	Low voltage (less than 195v)
Baxi Solo Error Codes
Fault Code	Possible Cause
FLASH FLASH ON	Fan error
FLASH OFF FLASH	Voltage less than 180V
FLASH OFF ON	Overheat lockout
FLASH ON FLASH	Printed circuit board (PCB) error
FLASH ON ON	Printed circuit board (PCB) fault
OFF OFF OFF	No power
ON FLASH FLASH	Circulation error or dry fire
ON FLASH ON	Thermistor error
ON OFF FLASH	Live and neutral reversed error
ON OFF ON	Ignition lockout error
ON ON FLASH	Printed circuit board (PCB) error
ON ON ON	Low voltage wiring harness error
Error Code E133 and E28
If you’re seeing either of these two error codes on your Baxi boiler, this is due to your condensate pipe being frozen. In the cold winter months this can happen easily as the condensate pipe runs outside. You can fix this issue by thawing out the pipe (if you feel confident to), find out everything you need to know about how to do it with our guide to thawing a frozen condensate pipe.

Ferroli

Ferroli iBoiler Error Codes
Fault Code	System Behaviour
A01	Ignition error – possible electrode fault or power too low, no gas or excessive condensate level
A02	Electrode or card error
A03	Heating sensor damaged, no water circulation or air in system
F04	Wrong card parameter setting
F05	Air pressure switch contact error – wrong flue baffle obstructed or not correctly sized
A06	No flame after the ignition phase – low pressure in gas system burner minimum pressure setting
F07	Air pressure switch error – contacts closed on activation of fan
A09	Gas valve error – wiring could be disconnected or error with gas valve
F10	Delivery sensor error, sensor damaged wiring shorted or disconnected
F11	Domestic hot water (DHW) sensor error – sensor damaged, wiring shorted or disconnected
A15	Fault F05 generated 5 times within the last 24 hours – possible error with the air pressure switch
A16	Gas valve error – wiring disconnected or faulty gas valve
A23	Card parameter error – possibly wrong card parameter setting
A24	Card parameter error – possibly wrong card parameter setting
F34	Supply voltage under 170V – electric mains error
F35	Faulty mains frequency – electric mains error
F37	Error with system water pressure, possible pressure too low or water pressure switch is damaged
F43	Exchanger protection intervention – could be because no system water circulation or there’s air in the system
F50	Controller DBM23B error – controller could have an internal error
F51	Controller DBM23B error – controller could have an internal error

Ferroli Modena HE System Error Codes
Fault Code	System Behaviour
A01	No burner ignition – possible electrode error, defective gas valve or incorrect inlet gas pressure
A02	Flame detected with the burner off – electrode defective main board defective
A03	High limit protection – possible flow temperature sensor not active or incorrectly located, no system circulation
A04	Flue gas fault – fault F07 happened 3 times in the last 24 hours
A05	Fan error – tachometer signal interrupted for 1 hour or longer
A06	No flame after the ignition phase – electrode error, flame unstable, incorrect valve gas offset or flue gas circuit obstructed
A41	Flow sensor error – sensor disconnected
A42	Flow sensor error – sensor damaged
F07	High fume temperature – the exchanger probe detects an excessive temperature
F10	Flow sensor error – sensor damaged, short circuited, sensor damaged or wiring broken
F11	Return sensor error – t-sensor damaged, short circuited, sensor damaged or wiring broken
F13	Exchanger probe error – t-sensor damaged, short circuited, sensor damaged or wiring broken
F14	Flow sensor error – t-sensor damaged, short circuited, sensor damaged or wiring broken
F15	Fan problem – tachometer signal interrupted fan connection or damaged debris in fan. You need to check and clean fan debris
F34	Supply voltage under 170v – electric supply error
F35	Irregular mains frequency – electric supply problem
F37	Incorrect system water pressure error – possible sensor damaged or pressure too low
F43	Exchanger protection activation – no system circulation air in system
F52	Flow sensor – fault sensor damaged
A61	Controller ABM03B error – controller has an internal error
A62	No communication between controller and gas valve – controller not connected or valve damaged
A63 / A64 / F66	Controller ABM03B error – controller internal error


Ferroli Modena HE Combi Error Codes
Fault Code	System Behaviour
A01	No burner ignition – possibly no gas, detection or ignition electrode fault, defective gas valve, incorrect inlet gas pressure
A02	Flame detected with the burner off – possibly caused by ionisation, defective electrode or main board defective. Check the printed circuit board (PCB) or ionizing electrode wiring
A03	High limit protection – flow temperature sensor not active, incorrectly located or no system circulation. Check the position of the flow sensor or check pump and radiator valves
A04	Flue gas fault – could be because F07 happened 3 times in the last 24 hours – check the flue
A05	Fan problem – tachometer signal interrupted for 1 hour or longer – check the wiring and the fan
A06	No flame after ignition phase – possible causes: detection electrode fault, flame unstable, incorrect valve gas offset, flue gas circuit
A41	Flow sensor disconnected – check the correct positioning and operation of the flow sensors
A42	Flow sensor fault – sensor needs changing
F07	High fume temperature – the exchanger probe detects an excessive temperature for over 2 minutes – check the exchanger.
F10	Flow sensor fault – possible causes: sensor damaged, short circuited or wiring broken check the wiring
F11	Return sensor fault – sensor wiring shorted or broken – check the wiring
F12	Domestic hot water (DHW) sensor fault – sensor damaged, wiring shorted or wiring disconnected – check the wiring
F13	Exchange probe fault – wiring shorted or wiring broken – check wiring
F14	Fan problem – tachometer signal interrupted fan connection. Fan damaged or debris in fan – check the wiring, the fan and clean debris
F15	Supply voltage under 170v – electric supply problem – the electrical system needs checking
F34	Irregular mains frequency – possible electric supply problem – the electrical system needs checking
F35	Incorrect system water pressure – possible cause is pressure too low or sensor damaged – the system may need filling or check the sensor
F37	External probe fault sensor damaged or short circuited – check the wiring
F39	Exchanger protection activation – possibly caused by no system circulation, air in the system or sensor damaged
F43	Flow sensor fault – sensor damaged – sensor needs changing
F52	Controller 041049G0 fault – controller internal error
A61	No communication between controller and gas valve controller – could not be connected or valve damaged
A62	Controller 041049G – internal error
A63 / A64 / F66	Controller DBM12 fault

Ferroli Discontinued Boiler Error Codes
DOMIcondens HE 26 C
OPTIMAX HE PLUS 31C boiler
OPTIMAX HE PLUS 38C boiler
Boilers	Fault Code	System Behaviour
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C	A01	No burner ignition
OPTIMAX HE PLUS 38C	A01	The burner fails to light
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A02	Flame present signal with burner off, possible electrical fault
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A03	Over temperature protection activation
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C	A04	Fume thermostat fault
OPTIMAX HE PLUS 38C	A04	Fume extraction duct safety device activation
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C	A05	Fan fault or fume pressure switch fault
OPTIMAX HE PLUS 38C	A05	Fan protection activated
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A06	No flame after the ignition phase
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F07	High fume temperature
DOMIcondens HE 26 C	F07	Card parameter
DOMIcondens HE 26 C	A09	Gas value fault
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F10	Delivery sensor 1 fault
DOMIcondens HE 26 C	F11	DHW sensor fault
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F11	Return sensor fault
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F13	Fume sensor fault
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F14	Delivery sensor 2 fault
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F15	Fan fault
DOMIcondens HE 26 C	A16	Gas valve fault
DOMIcondens HE 26 C	F20	Combustion control fault
DOMIcondens HE 26 C	A21	Poor combustion fail
DOMIcondens HE 26 C	A23	Set nominal system water pressure not reached within 4 minutes
DOMIcondens HE 26 C	A24	4 fillings within 24 hours
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A34	Supply voltage under 170V / 180V
DOMIcondens HE 26 C	A35	Faulty mains frequency
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A35	Mains frequency anomaly
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A37	Incorrect system water pressure
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A39	External probe fault
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A41	Sensor positioning
DOMIcondens HE 26 C / OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	F42	Heating sensor fault
DOMIcondens HE 26 C	A43	Exchange protection activation
DOMIcondens HE 26 C	A50	Gas valve fault
DOMIcondens HE 26 C	A51	Poor combustion fault
OPTIMAX HE PLUS 31C boiler / OPTIMAX HE PLUS 38C	A62	No communication between electronic controller and gas valve

Alpha

Alpha Boiler Fault Codes

Fault Code	Fault	Possible Cause
1	Ignition failure	Gas supply, pressure tubes, ignition electrode, flame sensor electrode, ignition generator, lead flame sensor, electrode lead, gas valve setting, gas valve printed circuit board (PCB)
2	Overheat boiler lock out	Pump or flow problem, blocked heat exchanger, air in heat exchanger, overheat thermostat, thermal fuse (if open circuit then replace primary heat exchanger)
3	High flue thermostat temperature	Blocked or restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault
4	Gas valve electrical connection fault	Gas valve lead connection fault, faulty gas valve or faulty printed circuit board (PCB)
5	Heating flow sensor fault	Flow sensor wire connections, flow sensor faulty
6	Domestic how water (DHW) sensor fault	DHW sensor wiring connection or DHW sensor faulty
8	Maximum number of resets	Refer to fault history codes
10	Primary system pressure low	Check expansion vessel pressure (1 bar), leak in system, expansion relief valve operated or primary pressure switch
12	Cylinder sensor fault (FlowSmart only)	Cylinder sensor wiring connections or cylinder sensor faulty
15	Internal wiring error	Check internal wiring connections to printed circuit board (PCB), Combi boiler domestic hot water (DHW) sensor X4, System boiler link X14
16	Fan fault	Fan wiring connections, fan fault or printed circuit board (PCB) fault
20	Flame sensing fault	Check flame sensing electrode and lead printed circuit board (PCB) fault
24	Control panel button fault	Jammed control panel or printed circuit board (PCB) buttons
25	Overheat lock out	Air in heat exchanger, blocked or restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault, pump fault, boiler or heating circuit valve closed
27	Insufficient primary flow	Blocked or restricted primary flow, air in heat exchanger, boiler or heating circuit valve closed, pump fault or primary flow sensor fault
29	Flue sensor fault	Sensor wiring connection or flue sensor faulty
31	Loss of communication with external control (Alpha Climatic)	Remote control or receiver connection wiring
37	Low supply voltage	Check mains power supply
38	Loss of flame rectification	Flame sensing electrode and lead, check flue gas recirculation, check the gas valve settings and check the fan speed settings
43	Loss of flame rectification	Check gas supply working, check flame sensing electrode and lead, check for flue gas recirculation, check the gas valve settings, check the fan speed settings
44	Safety lock out	Check external control (room thermostat) requests and rapid on/off hot tap requests
46	External sensor intervention	External sensor and cable damaged or wet, continuity of external sensor and circuit, check connection at X19 on printed circuit board (PCB) and sensor connecting block
47	Reduced burner output	Air in heat exchanger, restricted primary flow, heat exchanger air flow blocked, flue restriction, flue sensor fault or pump fault
51	Climatic RF communication fault	Batteries need replacing, distance between boiler and climatic control too great, interference object blocking signal (metallic)

E-Tec, E-Tec Plus, Evoke Combi Boilers Error Codes

Fault Code	Fault	Possible Cause
60	Pump error (stuck or there is an electrical pump fault)	Pump operation (may need to free the pump shaft), issue with pump wiring or pump replacement needed.
61	Air in the pump (restricted central heating flow)	Flow and Return valves may not be open, iIncorrect system pressure, system not purged properly or flow return valves are open.
70	Return/flow sensor Exchange from possible wiring fault	Issues with sensor wiring and connections. Issues with sensor resistance.
75 / 76	Return/flow sensor fault from possible failure of one or both sensors	Issues with sensor resistance.
SR	Service reminder	Service reminder countdown has reached 0 (this will not stop boiler from working) – boiler needs servicing.

Protec Plus Error Codes

Fault Code	Fault	Possible Cause
0A1	Ignition failure	Issue with gas supply. Ignition electrode position and spark issues.
0A2	Flame detection fault	Flame sensing electrode connections. A short circuit to the electrode or wires.
0A3	Overheat thermostat lock-out	Flame sensing electrode connections. A short circuit to the electrode or wires.
0A5	Fan speed fault	Problem with flue /ventilation. Issue with air inlet manifold and pipe. Damage or fault with fan. Fan wire connections.
0A7	High flue temperature fault	Air in the primary heat exchanger. System restrictions causing overheating. Flue run may have restrictions or blockages.
0A8	Flame circuit fault	Incorrect gas supply. Ignition electrode position and spark. Issues with flame sensing electrode gap and connections.
0A9	Gas valve electrical error	Valve connection issues. Main PCB. Gas valve operation issues. Gas contamination.
0A15	Flow and return sensor anomaly detected. (incorrect temperature value shown on sensor.)	Poor or incorrect circulation. External circuit influences. Problem with resistances of flow and return sensors.
0A16	Flow sensor temperature rise incorrect (time taken for flow temperature to rise is too long.)	System circulation issues. System volume or flow is too high. Boiler output is insufficient for the system.
0A17	Return sensor temperature rise incorrect (time taken for flow temperature to rise is too long.)	System circulation issues. System volume or flow is too high. Boiler output is insufficient for the system.
0A18	Flow and return sensor anomaly detected. Sudden temperature change detected on the flow or return sensor.	System circulation issues. Problem with operation of zone valves. Resistances and function of flow and return sensors needs checking.
0A21	Main PCB fault	Electrical connections. Water ingress in connections.
0A30	Flow sensor short circuit	Flow sensor connections and wires need checking. Water ingress in connections.
0A31	Flow sensor out of range. (sensor measures a temperature not in normal range.)	Problem with flow sensor connections and damaged wires. Sensor resistance values wrong.
0A37 – Pro Tec 50	Insufficient system flow (if the system flow is too low for a certain length of time boiler will switch off)	Flow switch reading needs checking. Restrictions or shut valves in system. Pump function issues. System pressure issues.
0A37 – Pro tec 70, 90, 115	Insufficient system pressure (if the system pressure is too low the boiler switches off.)	System pressure needs to be 1 – 2 bar if its not the pressure needs refilling to the correct amount
0A43	Return sensor short circuit	Problem with return sensor connections and wires. Water ingress in connections
0A44	Return sensor out of range. Sensor measures a temperature outside normal working range	Return sensor connections and damaged wires. Return sensor resistance values need checking.
0A80	Flow and return sensor connection fault (may occur after several minutes of boiler operation.)	Wires are not connected to the correct sensors.
0.00E+00	Flame sensing fault.	Flame sensing electrode connections need checking. Short circuit to the electrode or wire.
0.00E+00	Maximum number of resets reached. (Over 5 reset attempts have been reached within 15 minutes.)	Investigate initial fault code displayed. Power supply needs to be turned Off/On to clear this code
0.00E+00	Main PCB fault	All electrical connections need to be checked. Water ingress in connections.
0.00E+00	DHW sensor out of range (measures a temperature outside normal working range.)	DHW sensor connections and damaged cables. Issues with DHW sensor resistance values
0.00E+00	Low power supply voltage	Electrical socket connection issues. Problem with external power supply. Possible power disruptions
0.00E+00	Insufficient system pressure	System needs checking for circulation and restrictions. System pressure and gauge needs checking. Pressure switch and connections need checking.
0.00E+00	Flue sensor short circuit	Flue sensor connections and wires need checking. Water ingress in connections
0.00E+00	Flue sensor out of range (measures a temperature outside of normal working range)	Flue sensor connections, wires and flue sensor resistance values need checking.
0.00E+00	Flow and return sensor anomaly detected (the sensor shows an incorrect temperature value)	Poor or incorrect circulation / external circuit influences resistance of flow return sensors need checking
0.00E+00	Flow and return sensor anomaly detected (sensor shows incorrect temperature value)	M to O Connections need checking Compatible software on PCB needs checking
0.00E+00	Simple cascade communication error	Wiring connections needs checking on all boilers. Configuration, parameter 38.
FE94	Display PCB fault.	Electrical connections to display board need checking. Water ingress in connections. Damage to buttons or LCD screen.
FE95	External flow sensor out of range or short circuit/ External flow sensor measures a temperature outside of normal working range.	External flow sensor connections and wires need checking for damage. External flow sensor resistance values need checking to make sure they are between 5 and 0
FE96	External sensor fault	External sensor connections and wires need checking. Water ingress in connections. Boiler parameter settings are incorrect.
FE97	Boiler PCB configuration error (may occur if the main PCB or display PCB is changed.)	All electrical connections. Incorrect parameter settings on PCB. Press ‘-‘ CH button until ‘AUTO’ appears, then press and hold ‘RESET’ button until ‘bu1’ appears


Alpha Flashing Light Errors Codes

Fault Code	Fault	Possible Cause
No lights on	Electricity fault	Check your electricity supply
Illuminated red A or B	Burner has failed to light	Rotate selector switch to the reset position (3) and the ignition sequence will restart after a delay of about 30 seconds
Illuminated yellow B or C	Burner is alight	No action required
Flashing red A or B	Overheat thermostat has operated / Temperature sensor fault	Rotate selector switch to the reset position (3) to reset
Flashing yellow every 5 seconds or illuminated green D	Electrical supply to the boiler is on	No Action Required
Flashing yellow B or flashing Red A	Temperature sensor fault
Illuminated red A and flashing yellow B or Flashing red A and flashing red B	Blocked flue or fan fault
Flashing yellow or flashing Red A or Flashing (alternating) red A and flashing (alternating) yellow B	System pressure is very low and re-pressurisation is required
Illuminated red A and flashing yellow B	Pump fault or restricted flow
Flashing red A and Flashing red B and flashing yellow C	Temperature sensor wiring or flow and return connections incorrect
Flashing red A and flashing red B and flashing yellow C indicators	Flue temperature too high (air in the heat exchanger, heat exchanger blocked

Alpha E-Tec Regular Gas Boiler Error Codes

Fault Code	Fault	Possible Cause
1	Ignition failure	Check the gas supply, pressure tubes, ignition electrode, flame sensor electrode, ignition generator or lead flame sensor, gas valve setting and PCB.
2	Overheat boiler lockout	Pump or flow problem. Caused by a blocked heat exchanger, air in heat exchanger, overheated thermostat, thermal fuse (if open circuit then replace primary heat exchanger).
3	High flue thermostat temperature	Blocked or restricted primary flow. Heat exchanger air flow blocked, flue restriction, flue sensor fault.
4	Gas valve electrical connection fault	Gas valve lead connection fault. Faulty gas valve or faulty PCB.
5	Heating flow sensor fault	Flow sensor wire connections. Flow sensor faulty.
6	Internal wiring error	Incorrect wiring configuration detected. Internal wiring connections to PCB need checking.
7	Chimney sweep function is active	Chimney sweep function is active. E07 is displayed on the climatic remote control.
8	Maximum number of resets	Refer to fault history codes (INFO menud9)
12	Cylinder sensor fault (FlowSmart only)	Cylinder sensor wiring connection – cylinder sensor faulty.
16	Fan fault	Check fan wiring connection, fan fault or PCB fault.
20	Flame sensing fault	Check flame sensing electrode and lead PCB for faults.
23	Heating return sensor fault	Incorrect return sensor resistance value – return sensor wire connections or sensor could be faulty.
24	Control panel button fault	Control panel button is stuck in the ‘on’ position – check for jammed control panel buttons or jammed PCB button.
27	Insufficient primary flow	Blocked or restricted primary flow. Air in heat exchanger, boiler or heating circuit valve closed, pump fault or primary flow sensor fault.
29	Flue sensor fault	Check sensor wiring connection – flue sensor faulty.
31	Loss of communication with external control (Alpha Climatic)	Remote control or receiver connection wiring.
37	Low supply voltage	Check mains power supply.
38	Loss of flame rectification	Check flame sensing electrode and lead and for flue gas recirculation. Check or adjust the gas valve settings. Check or adjust the fan speed settings.
43	Loss of flame rectification	Check gas supply/working pressure, flame sensing electrode and lead, check for flue gas recirculation, check/adjust the gas valve settings, check/adjust the fan speed settings.
44	Safety lockout	Check external control (room thermostat) requests. Rapid on/off hot tap requests.
45	High-temperature difference	The boiler is detecting an unexpected increase between the system flow and return sensors. Boiler output is limited for boiler protection and once restored the boiler resumes regular operation.
46	Optional thermostat intervention	No continuity of optional thermostat circuit – check the optional thermostat and cable are not damaged or wet.
47	Reduced burner output	Flue thermostat has sensed high flue gas temperature and reduced the burner output to prevent damage. If the temperature continues to rise the boiler will lockout and the E03 error code will be displayed. This could be due to air in the heat exchanger, restricted primary flow or heat exchanger air blocked.
49	Return sensor high temperature intervention	Return sensor has detected a high temperature on the exchanger return circuit.
51	Climatic RF communication fault	The error between the communication of the climatic transmitter and boiler receiver. Could mean the batteries need replacing or the distance between the boiler and climatic control is too great or a metal object is blocking the signal.
70	Return flow sensor error	Possible wiring faults sensor is incorrectly fitted or the system is blocked – check the sensor wiring and connections, also check sensor resistance and circulation.
71	No primary temperature increase detected	From ignition the boiler detects no temperature rise in the primary circuit – check system filling and venting, air locks preventing flow check, blocked flow or closed valves.

Ariston

Ariston Error Codes
Fault Code	Boiler Model	Possible Cause
Central Heating Circuit
101	All Boilers	Overheat
102	E-Combi Evo E-System Evo Clas He Evo (Combi and system)	Pressure sensor error
103	All Boilers	Insufficient circulation
104	All Boilers	Insufficient circulation
105	All Boilers	Insufficient circulation
106	All Boilers	Insufficient circulation
107	All Boilers	Insufficient circulation
108	All Combi Boilers	Insufficient water (request filling)
109	Clas net one / Clas one Combi Clas system one	System pressure greater than 3 bar
110	All Boilers	Central heating Flow temperature probe circuit open / short circuit
112	All Boilers	Central heating return temperature probe circuit open / short circuit
114	All Boilers	External sensor circuit open / short circuit
116	All Combi and System Boilers	Floor thermostat contact open
118	All Boilers	Heating delivery probe problem
1p1	All Boilers	Insufficient circulation indication
1p2	All Boilers	Insufficient circulation indication
1p3	All Boilers	Insufficient circulation indication
1p4	Clas Net one Combi Clas one Combi Clas System one	Insufficient circulation indication
D.H.W Circuit
202	Clas HE evo Clas he evo system E-combi evo E-system evo	2 bottom storage temperature probe open/short circuit
204	Clas HE evo Clas he evo system E-combi evo E-system evo	Solar collector temperature probe open/short circuit
205	E-combi one E-System one Clas Net one Combi Clas one Combi	Domestic hot water in probe open circuit
207	Clas HE evo Clas he evo system E-combi evo E-system evo	Solar collector overheating
208	Clas HE evo Clas he evo system E-combi evo E-system evo	Collector frost protection temperature
Internal printed circuit board (PCB)
301	All Boilers	EEPROM error
302	All Boilers	Communication error
303	All Boilers	Main printed circuit board (PCB) error
304	All Boilers	Too many resets (> 5) in 15 minutes
305	All Boilers	Main printed circuit board (PCB) error
306	All Boilers	Main printed circuit board (PCB) error
307	All Boilers	Main printed circuit board (PCB) error
3P9	E-combi one E-System one Clas Net one Combi Clas one Combi Clas System one	Schedule service
External printed circuit board (PCB)
407	Clas HE evo Clas he evo system E-combi evo E-system evo	7 Room sensor circuit open/short circuit
Ignition and Detection
501	All Boilers	No flame detected
502	All Boilers	Flame detected with gas valve closed
504	All Boilers	Flame lift
5P1	All Boilers	1st ignition failed
5P2	All boilers	2nd ignition failed
5P3	All Boilers	Flame cut-of
Air Inlet / Flue gas outlet
604	CLAS HE R E-Combi Evo E-System EVO Clas HE evo Combi Clas HE evo System	Insufficient fan speed
610	All Boilers	Thermofuse open
612	Clas HE Evo Combi Clas He Evo System E-Combi Evo E-system Evo Clas net one combi Clas one combi Clas system one	Fan speed has incorrect measurement
Multi-zone Heating
701	E-Combi Evo E-System EVO Clas HE evo combi Clas he evo system	Zone 2 outgoing sensor defective
702	E-Combi Evo E-System EVO Clas HE evo Combi Clas HE evo System	Zone 2 return sensor defective
703	E-Combi Evo E-System EVO Clas HE evo combi Clas he evo system	Zone 3 outgoing sensor defective
704	E-Combi Evo E-System EVO Clas HE evo Combi Clas HE evo System	Zone 3 return sensor defective
705	E-Combi Evo E-System EVO Clas HE evo combi Clas he evo system	Hydraulic separation sensor defective
706	E-Combi Evo E-System EVO Clas HE evo combi Clas he evo system	Zone 2 overheating
707	E-Combi Evo E-System EVO Clas HE evo Combi Clas HE evo System	Zone 3 overheating


Clas Net One, Clas One, E-Combi and E-System Error Codes
Fault Code	Possible Cause
External printed circuit board (PCB)
411	Room sensor circuit open or short circuit zone 1
412	Room sensor circuit open or short circuit zone 2
414	Room sensor circuit open or short circuit zone 3
Multi-zone Heating
701	Send sensor defective (Zone 1)
702	Send sensor defective (Zone 2)
703	Send sensor defective (Zone 3)
711	Return sensor defective (zone 1)
712	Return sensor defective (zone 2)
713	Return sensor defective (zone 3)
722	Overheating in zone 2
723	Overheating in zone 3
750	All heating zones locked

ATAG

ATAG Boiler Error Codes
When your ATAG boiler has an error, you will see an error symbol. This symbol is normally accompanied by one of the codes in the tables below.
Fault Code	System Behaviour
10	Outside sensor error
20	Flow sensor error
40	Return sensor error
61	Bus communication error
78	Water pressure out of range
105	Venting program active when power turned on / interrupted (runs for 7 mins)
110	Exceeded safety temperature
111	Exceeded maximum pressure
119	X2 link position 4 and 5 missing
129	Fan doesn’t start
133	No flame after 5 ignition attempts
151	Fan error or control unit defective (speed control is not achieved)
154	Return greater than flow – flow temperature increases too fast
101	Overheat error
102	Pressure sensor fault
104	Flow check failed
108	Pressure needs filling to < 0.5 bar
1P4	Pressure needs filling to 0.5 – 0.8 bar
109	Pressure > Pmax error
110	Send probe damaged
112	Return probe error – could be damaged
114	Outdoor sensor error – could be damaged
141	Central heating flow switch is open
201	Domestic hot water (DHW) probe damaged
203	Tank probe damaged
303	Printed circuit board (PCB) error
304	Too many resets have occurred
501	No flame detected
612	Fan fault – fan isn’t starting up
IC & IS Combi Boiler Error Codes
Fault Code	System Behaviour
50	Domestic hot water (DHW) sensor error
117	Pressure greater than 3 bar or pump pressure increase is too high
118	Pressure less than 1 bar or pump pressure increase too low (no pump detection).
Other Fault Codes
If you see a spanner symbol this could be one of two things; firstly it could mean your boiler is in service mode. Secondly it could be blocking, if the boiler is blocking the code is only temporary and will clear itself or will lock the boiler after several attempts if the error keeps on occurring.
ATAG Error code 133
If you are seeing the error code 133, your boilers flame is failing after 5 ignition attempts. This could be down to your condensate drain pipe freezing. A frozen condensate pipe is something that is often easily fixed, you can find out how in this guide to defrosting a condensate pipe.

Biasi

Biasi Boiler Error Codes
Fault Code	Fault Image	System Behaviour
ER 01 + Reset	N/A	Lack of burner ignition on safety lockout
ER 02 + Reset	N/A	Safety thermostat intervention lockout
ER 03 + Reset	N/A	General lockout
ER 04 +	Faulty primary circuit (no water or absence of flow)
ER 05 +	Faulty fan control system
ER 06 +	Faulty c.h. temp. probe NTC
ER 07 +	Faulty d.h.w. temp. probe NTC
ER 08 +	Faulty external temp. probe NTC
ER 09 +	Faulty flue temp. probe NTC
ER 10 + reset	N/A	Flue probe intervention lockout
N/A	Flame detection error (An flashing + number error flashing
ER + 14 + Reset	N/A	Faulty pump or primary temperature above 105°C
ER + 14 + Reset	N/A	Faulty pump or primary temperature above 105°C
ER + 14 +	Absence of flow from temperature gradient (>2K/s)/td>
Li	N/A	Primary circuit temp. limit during d.h.w. operation
—	N/A	Boiler Stand-By, hyphens are turned on in sequence to simulate running /antifreeze protection activated)
N/A	Boiler Stand-By, hyphens are turned on in sequence to simulate running /antifreeze protection activated)
N/A	Filling request: The boiler works regularly and the display shows all the icons, but the signal FL is flashing every 1 sec.
N/A	Insufficient pressure: The boiler stops displaying the water lack error.
30c	N/A	Boiler waiting for heat request
N/A	Boiler in summer mode (d.h.w.). The primary circuit temperature is displayed.
N/A	Boiler in winter mode (c.h.+ d.h.w.) The primary circuit temperature is displayed.
N/A	Boiler on demand for d.h.w. power. The d.h.w. temperature is displayed. / Boiler on demand for c.h. power.
N/A	Burner ignition (spark)
N/A	Flame present (Burner on)
N/A	Pre-heating function 3 stars DHW comfort. This information is not displayed. It will be possible to check its state in the section “INFO” value “cF” (the signal “cF” is alternated to the CH temperature value until the end of this function). You can enter the function pushing the buttons 12 and 13 together. The function is confirmed showing ON or OFF alternating for 5 sec. This function is always active at every hour (it’s not possible to set the time slots unless a remote control is connected).
N/A	Pre-heating function 3 stars DHW comfort. This information is not displayed. It will be possible to check its state in the section “INFO” value “cF” (the signal “cF” is alternated to the CH temperature value until the end of this function). You can enter the function pushing the buttons 12 and 13 together. The function is confirmed showing ON or OFF alternating for 5 sec. This function is always active at every hour (it’s not possible to set the time slots unless a remote control is connected).
N/A	Boiler in anti-freeze phase (bP flashing + temperature flashing)
N/A	Boiler in antifrost phase (AF flashing + temperature flashing)
N/A	Set c.h. (all other symbols are disabled)
N/A	Set d.h.w. (all other symbols are disabled)
N/A	Pump activated for the post-circulation phase (Po flashing + temperature flashing)
N/A	Delayed burner ignition for setting the system (uu flashing + temperature flashing)
N/A	Maintenance required The wrench symbol is flashing (without showing any error)
LP	N/A	Boiler in chimney sweep in function. The activation of the chimney sweep occurs configuring the “parameter P09=01” and is visualised: LP= minimum dhw hP= minimum heating cP= maximum heating dP= maximum dhw. The transition occurs with keys 16 (increase) and 15 (decrease) dhw temperature. The writing on the display alternates.
N/A	Boiler in chimney sweep in function. The activation of the chimney sweep occurs configuring the “parameter P09=01” and is visualised: LP= minimum dhw hP= minimum heating cP= maximum heating dP= maximum dhw. The transition occurs with keys 16 (increase) and 15 (decrease) dhw temperature. The writing on the display alternates.

Daikin

D2CND Combi Gas Boiler Error Codes
Fault Code	Possible Cause
10-64	Gas valve circuit error, try resetting boiler
10-65	Gas valve current fault, try resetting the boiler
11-64	Ignition error – possible fault with valve on the gas line due to it being open. Try resetting the boiler after the third unsuccessful ignition.
11-65	Flame stabilisation error – wait for the boiler ignition trial
11-66	Flame Signal loss in safety time – try to reset the boiler after 3rd unsuccessful ignition
11-67	Flame loss during operation. This is a temporary error, wait for the boiler to re-ignite.
12-64	Ion control deviation is too big – try resetting the boiler
12-65	Ignition scott actuators error – try resetting the boiler
12-66	Ion base value lower than the upper factory limit, try resetting the boiler
12-67	Ion base value exceeds the upper factory limit – try resetting the boiler
12-68	Ion base value differs from the previous value – try resetting the boiler
12-69	Offset adaptation at limit
13-64 / 13-65	Fan speed error – try resetting the boiler
16-64	Flue temperature signals overheating, the flue gas discharge path needs checking. Try resetting the boiler
1J-64	High limit thermostat signalising overheating. Check the valve of the radiators in the heating, check if the Combi boiler water pressure is low, if it is then the heating circuit needs filling with water
80-01	Return temperature sensor error – reset the boiler
81-01	Flow temperature sensor error – try resetting the boiler
81-65	Domestic hot water (DHW) temperature sensor error. The boiler will continue in operation but solar sensor has an error .
8A-46	Freeze protection – the boiler won’t operate if flow temperature sensor reads a value that is less than 1°c
8H-65	Flow temperature steep rise – the radiator valves may not be open enough to circulate water
E1-64	Flame detected before burner operation – try resetting the boiler
E1-65	Internal SCOT system error. Perform reset if needed
E1-66	Calibration condition error, wait for burner to restart
E1-67	Missing calibration – try resetting the boiler
E1-68	Ion base value is outside the factory limits or saved incorrectly – try resetting the boiler
E1-69 / E1-70	Parameter CRC fault – try resetting the boiler
E1-71	EK lockout failure – this is a permanent error
E1-72	SCOT flame amplifier – reset the boiler
E1-73	Printed circuit board (PCB) error – try resetting the boiler
H9-01	Outside sensor fault – try resetting the boiler
HC-01	Domestic hot water (DHW) temperature sensor error. The boiler will continue to operate but you need to contact a heating engineer
HJ-08	High system pressure – the boiler needs to discharge water down to 0.8 bar
HJ-09	Low system pressure – increase the system pressure to 0.8 bar
HJ-10	Water pressure sensor fault
J6-01	Flow temperature sensor overheating due to a blocking fault or a lockout error – the valves of the radiator heating circuit may have an issue or the water pressure is low and needs filling
J6-20	Return temperature sensor overheating due to a blocking fault or a lockout error – try resetting the boiler
J6-21	Return temperature is higher than flow temperature. Burner operates itself after a small amount of time but if the problem repeats you need to contact a heating engineer
JJ-64	Supply voltage is below low limit
U2-01	Supply voltage is above high limit, your boiler should continue to operate but you need to contact a heating engineer
U4-65	OpenTherm room thermostat connection is defective – your boiler will continue to operation but the thermostat is out of operation
U4-66	CAN-bus timeout
U4-67	Remote reset supervision, switch off the power at the mains – if problem repeats contact a heating engineer
UA-64	Blocking during boiler chip card (BBC) update
UA-65	Printed circuit board (PCB) requires a boiler chip card (BCC) update
UA-66	Boiler chip card ID (BCC-iD) of internal Electrically Erasable Programmable Read-Only Memory (EEPROM) is inconsistent
UA-67	Boiler chip card (BCC) is missing
Error Code HJ-08	If you are seeing the error code HJ-08 this could be due to a high system pressure. To resolve this issue you need to discharge the water down to 0.8 bar. As well as this, you should also bleed your radiators. To do this check out our handy guide to bleeding radiators.

Firebird

Firebird Boiler Error Codes
Fault	Possible Cause
E1	Control thermistor fault
E2	Flue thermistor fault
E3	Flue thermistor fault
E5	Burner fault (possibly burner lockout)
Thermostat at a high limit (cuts off)	Reset boiler

Occasionally some things can go wrong, that’s why we’ve created our handy at-a-glance table of Firebird error codes and a guide to Common Firebird Problems and Repair.

Should you need professional help with your broken boiler, then simply use one of our enquiry forms and we will connect you with the best heating engineers local to you.

Grant

Grant Boiler Error Codes
Fault Code	Cause of Problem
No display	12V transformer failure
PP1	Inlet (return) water temperature sensor failure
PP1	Inlet (return) water temperature sensor failure
PP2	Discharge gas sensor failure
PP3	Coil temperature sensor failure
PP4	Return gas sensor failure
PP5	Ambient temperature sensor failure
PP6	Discharge gas overheat protection
PP7	Winter anti-freeze protection in operation
EE1	High pressure – circulating pump failure or circuit air locked
EE2	Low pressure
EE3	Open circuit between PCB terminals 23-24
EE4	Supply L and N are reversed
EE8	Communication failure
Flashing on and off	Defrosting
E01	Internal control fault
sHr	HP flow sensor short / HP return sensor short
OPn	HP flow sensor open / HP return sensor open
SUP	Supply sensor short / Supply sensor open

OUTDR	Outdoor sensor short / Outdoor sensor open
C2849	Fault C; Chassis Code Problem is controller area network wiring bus and modules. fault two; MFG – Manufacturer Specific Fault eight; Ignition System Or Misfire fault four; BBV Sensor Circuit Low Voltage fault nine; Kick-Down Switch Failed Short
U2453	Fault U: Network Code Problem is climate control system, lighting, airbags, etc.. fault two; MFG – Manufacturer Specific fault four; Transmission fault five; TP Sensor Learn Not Complete fault three; Transmission Control Module Reprogrammable Memory


Grant Boiler Error Description
Grant Fault	Fault Description
Boiler Will Not Start	Low pressure cut-out activated No electrical supply to burner Check controls are switched on and calling for heat Boiler thermostat and/or overheat thermostat faulty
Burner lights but goes to lock-out	Fault with burner No fuel supply Oil tank empty Fire valve closed Fire valve closed. Fuel line filter is blocked Oil supply line is air locked Excessive combustion air Fault with burner
Burner fires but smoke visible from flue or high smoke number	Insufficient combustion air supply to burner Incorrect or faulty nozzle fitted Fuel pressure too high
Burner pulsates	Insufficient combustion air supply to burner
Burner cycles On and Off	Contaminated combustion air (balanced flue) Insufficient oil flow to burner due to restriction in supply line Excessive combustion air
Fumes and puffing on starting	Flue is blocked Insufficient flue draught Flue pipe or liner is too large or existing stack is unlined Insufficient combustion air supply to burner
Flame slow to stabilise on starting	Insufficient combustion air supply to burner Fuel pressure too low
Oil smells	Oil leak in supply line or burner
Combustion fume smells	Leak around boiler cleaning door Burner not correctly fitted on mounting flange Burner seal ‘O’ ring damaged or missing. Leakage around flue connection
Overheat thermostat operating	Faulty boiler thermostat Thermostat sensor not connected to printed circuit board (PCB) – Vortex Combi only Faulty overheat thermostat
No water flowing from hot tap	Mains water supply is not connected to cold water inlet of boiler One or more isolating valves, stop cocks, etc. in the pipework are closed The cold water isolating valve in the boiler is closed There is a blockage (or blockages) in the pipework
No hot water operation	Hot tap is not connected to hot water outlet of boiler Insufficient flow of water through boiler Boiler cold water and hot water connections reversed Thermostatic mixing valve incorrectly fitted Pump is not operating in hot water mode Diverter valve microswitch(es) faulty Diverter valve microswitches not operated Diverter valve seized Diverter valve diaphragm failed
Low water temperature at tap	Flow of water through boiler too high Boiler thermostat incorrectly set Thermostatic mixing valve incorrectly set Faulty boiler thermostat Pump speed setting too low Pump is incorrectly fitted
Hot water for short period only	Burner not firing for hot water (after a short time) Burner oil pressure set too low at oil pump Incorrect oil nozzle fitted to burner
No operation on heating	Timeswitch either not set, or not in an ‘ON’ period Timeswitch not operating Faulty timeswitch Faulty timeswitch switch contacts Timeswitch OK but not switching boiler on Heating switch set to ‘HOT WATER ONLY’ Room thermostat not calling for heat Faulty room thermostat No room thermostat or external timeswitch connected to boiler
Flow temperature low	Boiler thermostat is set too low Boiler thermostat faulty Boiler is underfired Combustion setting of burner incorrect Boiler heat exchanger is sooted up


Grant Vortex / Eco / Pro Boiler Error Codes
Fault Code	Cause of Problem
No fuel supply	Insure that an adequate supply of fuel is available and that the fuel supply valve is open – check the condition of the fuel filter and clean if necessary, ensure fuel supply is reaching burner and vent pump
No Electricity Supply	Ensure electricity supply to the boiler is switched on and that all controls are calling for heat – ensure that the overheat thermostat has not tripped, reset if necessary and check the mains supply
Burner not starting – fuel and electricity supplies present	Reset boiler on the burner control box – if it is lit refer to burner fault finding charts
Burner lights but goes to lock out	If the flame is unstable check the combustion setting
Visible smoke from flue or high smoke number	Insufficient air supply. Check the air damper setting and the condition of the fan check room ventilation, check the nozzle size and type, fuel pressure may be too high, check and adjust
Burner pulses	Insufficient air supply – check the air damper setting and the condition of the fan, check room ventilation
Flame slow to stabilise during start up	Insufficient air supply – Check the nozzle size and type as fuel pressure may be too low, check and adjust insufficient draught clean boiler heat exchanger and check condition of flue
Water temperature low	Undersize nozzle and or low fuel pressure check condition of boiler heat exchanger and clean if necessary. Check the boiler thermostat, check the combustion setting, check the condition of the fuel filter
Boiler operating an overheat thermostat	Faulty boiler thermostat – no circulation, check circulating pump, check for air lock
Fumes and puffing during starting	Check the condition of the chimney to ensure it is not blocked and is high enough to produce the required draught – check that there is an adequate air supply near the burner fan is not drawing products out of the burner
Oil odours	Check all fuel line connections and remake as necessary
Combustion fumes smell	Check boiler cleaning cover and seal are correctly fitted, check burner is correctly fitted onto flange, check flue is correctly sealed into flue outlet of boiler, check the condensate pipe and trap are operating correctly

Grant Vortex Blue Error Codes
Fault Code	Cause of Problem
Red blinking light	Presence of a false flame signal before heat request
Red blinking light	Presence of false flame signal during pre-purging
Red blinking light	Presence of false flame signal during post-purging or pre-heating
Red steady on	UV sensor defective or dirty oil valve defective fault – ignition transformer badly regulated burner, oil fuel not present
Red blinking light	Badly adjusted burner, oil valve defective or dirty UV sensor defective or dirty
Red and orange blinking inverted	Error with oil valve internal control circuit that drives the oil valve error
Red green blinking inverted	Internal memory error
Orange green blinking inverted	Check presence of voltage, check the condition of the fuses, check that safety thermostat is not in lockout
Off	Eliminate the extraneous light
Off	Check that plugs and sockets are connected properly
Red blinking light	Eliminate the extraneous light
Red steady on	Clear it / replace it / check the pressure and output of the fuel / check air output change nozzle check the coil od solenoid valve
Green blinking light	Set the air according to the instructions of the manual or replace

Grant Vortex Eco Error Codes
Fault Code	Cause of Problem
Motor fails to run	No electrical supply to boiler check on/off switch is on – it should be neon lit
Lock-out light not lit	Fuse has blown – check reason for failure
Motor fails to run	No power to burner motor
Burner lock out	Burner motor capacitor fault check and replace if necessary

Grant Vortex Pro Combi Error Codes
Fault Code	Cause of Problem
Power supply	Check that fused spur for heating system and boiler is switched on – check that the electricity supply has not failed
Heating system controls	Check that the timer or programmer is working and set to an on period
Boiler controls	Check boiler on/off switch is set to on – check that power indicator on and control panel is lit
Burner	Check the burner lockout reset button is lit, if yes press the reset button to start the burner if burner fails call an engineer
Heating system	Check the heating system water pressure
power	If the boiler is not lit it could be a problem with power supply to the boiler switched off or possibly blown a fuse
DHW pump	If flashing this indicates either a store thermistor or PCB fault
Flow	If the boiler is not lit when a hot tap is opened this could mean there is a lack of water flow or possible flow switch problem
Demand	If not lit this indicates either timer or programmer is not calling for hot water / switch is not set to constant
Burner	If flashing this indicates a PCB fault

Intergas

Intergas Boiler Error Codes
Fault Code	System Behaviour
10, 11, 12, 13, 14	Sensor fault S1
20, 21, 22, 23, 24	Sensor fault S2
0	Low system pressure
0	Sensor fault after self check
1	Temperature too high
2	S1 and S2 interchanged
4	No flame signal
5	Poor flame signal
6	Flame detection fault
8	Incorrect fan speed
27	Shortcut outside sensor temperature
29, 30	Gas valve relay faulty

Intergas Xtreme and Xclusive Boiler Error Codes
Fault Code	System Behaviour	Possible solution / cause
F000	Sensor defect	Heat exchanger sensor needs replacing.
F001	Temperature too high during central heating demand	Air could be in system, central heating system needs bleeding. There could be an error with the pump & it could need replacing.
F002	Temperature too high during domestic hot water (DHW) demand	The wiring of DHW sensor needs checking, possible breakage.
F003	Flue gas temperature too high	Heat exchanger needs checking for contamination.
F004	No flame during startup	Gas valve is closed. Condensation drain is blocked and ignition needs checking.
F005	Flame disappears during operation	Condensation drain could be blocked, the air supply duct and flue needs checking for possible recirculation or blockage of flue gases.
F006	Flame simulation error	Gas valve could need replacing or burner controller could need replacing.
F007	No or insufficient ionisation flow	Wiring of ionisation/ignition pin could have a breakage shut down and could need replacing.
F008	Fan speed incorrect	Fan cable needs checking, fan or burner controller could need replacing.
F009	Burner controller has internal fault	Burner controller needs replacing.
F010, F011	Sensor fault	Possible issue with heat exchanger sensor, breakage or not connected properly.
F012	Sensor 5 fault	Wiring for flue gas sensor needs checking, possible breakage.
F014	Mounting fault sensor	Heat exchanger sensor is not mounted correctly and needs to be mounted properly.
F015	Mounting fault sensor S1	Central heating flow sensor is not mounted correctly and needs mounting properly.

Johnson and Starley

Fault Image	System Behaviour
	Ignition lockout
	High limit error
	No tacho from fan
	High flue gas temperature
	Flame circuit error
	Valve drive circuit error
	Dual sensor error
	Default lockout
	Remote reset lockout
	ADC error
	CRC error – SW switch
	Flame signal lost 5 times in 4 minutes.
	Boiler flow temp sensor open circuit
	Domestic hot water (DHW) sensor short
	Domestic hot water (DHW) sensor open
	Low mains voltage
	Water pressure error
	OpenTherm sensor shorted to earth
	Water pressure too high
	No water pressure signal received from MMI
	Boiler return temp. sensor open circuit
	Flue gas temperature sensor short
	Flue gas temperature sensor open circuit
	Communication MMI – CVBC lost

Johnson & Starley Boiler Error Codes

Fault Code / Fault Image	System Behaviour
1	Flame lockout after several ignition attempts
2	False flame
3	High water temperature limit
5	No tacho from fan
8	Flame circuit error
9	Valve driver circuit error
11	Flow/return sensor calibration error
12	Default lockout
13	Elapsed the number of retrials
21	ADC error
26	Flame signal lost 5 times in 4 minutes
31	Centra heating supply sensor error (open or short)
44	Central heating return sensor error (open or short)
7	High flue gas temperature
25	CRC error
30	Boiler flow temperature sensor short circuit
31	Boiler flow temperature sensor open circuit
32	Domestic hot water temperature sensor short circuit
33	Domestic hot water temperature sensor open circuit
34	Low mains supply voltage
37	Low system water pressure
40	High system water pressure
41	No water pressure signal received from MMI
45	Flue gas temperature sensor short circuit
46	Flue gas temperature sensor open circuit
47	Water pressure sensor open circuit
99	Communication MMI -ESYS lost
E01	Ignition lockout
E02	False flame lockout
E03	Overheat lockout
E05	Fan fault
E08	Flame circuit failure
E09	Valve feed back error
E12	EEPROM lockout
E15	Sensor drift lockout
E16, E17, E18	Sensor stuck lockout
E21	ADC lockout
E33	Return thermistor fault
E34	Low power supply lockout
E35	Flow thermistor fault
F07	Exhaust sensor fault
F13	Remote reset lockout
F37	Low water pressure
F40	Water pressure too high
F47	Water pressure sensor not connected
F52	Domestic hot water (DHW) sensor fault
F53	Flue temperature sensor lockout

Keston

C36 Combi Gas Boiler Error Codes

Fault Code	Possible Cause
E01	Ignition failure – the boiler has attempted to light 5 times and not succeeded – check the gas supply is on
E02	False flame – possibly a problem with the power supply
E03	Boiler overheat – check that any valves to the heating circuit have not been shut down, no air in the system and that the water pressure is correct
E05	Fan failure – boiler cannot detect fan rotation – check fan operation and both connectors onto fan
E07	Flue overheat – check combustion and flue temperature vs. return temperature – the flue temperature should be no more than 10C above return temperature. Possible heat exchanger fault.
E08	Flame circuit error – possible control box fault
E09	Valve drive error – possible gas valve or control box fault
E10	Control box errors – possible faulty control box
E11	The automatic test for calibration of flow and return sensors has failed – check both flow and return sensors are located on the correct pipes and are producing the correct readings
E12 to E22	Control box errors – possible faulty control box
E23	Water filling error – check water pressure sensor
E24	Water pressure lost 4 times in 24 hours – possible leak, check system and boiler
E25	Control box errors – possible faulty control box
E26	Flame drop out – check for obstruction of the flue and/or air terminals, blockage/freezing of the drain pipe or a low gas supply (LPG).
E30	Flow sensor short circuit – check connections to flow sensor
E31	Flow sensor open circuit – check connections to flow sensor are in place
E32	DHW sensor short circuit – check connections to domestic hot water (DHW) sensor
E33	Domestic hot water (DHW) sensor short circuit – check connections to DHW sensor are in place
E34	Mains supply voltage < 180V – may be a problem with your power supply
E35	Mains supply frequency incorrect – may be a problem with the power supply
E37	Water pressure error – increase the system water pressure
E38	Reset key fault – replace fascia PCB
E40	Water pressure too high
E41	Communication error between fascia and control box – check cables
E43	Return sensor short circuit – check connections to return sensor
E44	Return sensor open circuit – check connections to return sensor are in place
E45	Flue sensor short circuit – check connections to flue sensor
E46	Communication error between fascia and control box – check cables
E99	Flue sensor short circuit – check connections to flue sensor are in place
S30 System Gas Boiler Error Codes

Fault Code	Possible Cause
0	The boiler is in standby mode awaiting either a central heating call or hot water demand
C	The boiler has a call for central heating / hot water but the appliance has reached the desired temperature set on the boiler
C And Burner Light	The boiler is operating for central heating / hot water
F And Burner Light	The boiler is operating in frost mode
F0	Boiler Chip Card (BCC) not fitted
F6	Outside sensor failure
F7	Low mains voltage
F9	Printed circuit board (PCB) Fault
L5	5 boiler resets in 15 minutes
L6	False flame lockout
C0	Boiler Chip Card (BCC) activation fault
C2	Boiler Chip Card (BCC) fault
F1	Low water pressure
L1	Flow temperature overheat
F2	Flame loss
L2	Flame loss
F3	Fan fault
F4	Control / No flow thermistor
F5	Return thermistor
C40 C55 Combi Gas Boiler

Fault Code	Possible Cause
Enn	Fault causing a boiler shutdown
E00	Flame detected when not expected – check boiler earth and probe condition
E02	No ignition after restart – check gas supply, gas valve operation and ignitor electrode spark generation
E03	Gas valve faulty or not connected
E04	Power has been reset whilst boiler was in lockout
E11	Internal electronics error – rest or replace control box
E18	Flow overheat – check water circulation
E19	Maximum return temperature exceeded – check circulation
E25	Flow temperature increased too quickly – check water circulation
E30	Difference between flow and return temperatures too high – check circulation.
E31	Flow thermistor short circuit – check/replace connections/thermistor
E32	Return thermistor short circuit – check/replace connections/thermistor
E36	Flow thermistor open circuit – check/replace connections/thermistor
E37	Return thermistor open circuit – check/replace connections/thermistor
E44	Low water pressure

Main

Main Boiler Error Codes
Fault Code	System Behaviour
E168	Error code E168 could mean that your boiler has detected a problem but can’t work out exactly what it is;
E20	Central Heating NTC Fault indicate faulty components. You should make a note of the displayed error code
E28	PCB Fault indicate faulty components
E50	Hot Water NTC Fault indicate faulty components
E110	Safety Thermostat operated – displayed when the primary water pressure is less than 0.5 bar. After repressurising the system the boiler should operate. Your installer will be able to advise you about the method of repressurising.
E119	Water pressure switch not operated – displayed when the primary water pressure is less than 0.5 bar. After repressurising the system the boiler should operate. Your installer will be able to advise you about the method of repressurising
E33	Interruption Of Gas Supply or Flame Failure indicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected. Ensure that the gas supply has not been turned off, and turn the selector switch to the reset position and hold for at least 5 seconds. If the boiler does not relight, or the code is displayed regularly.
E60	Fan or fan wiring fault
Main Error Code E133	A Main boiler showing the error code E133 means that the condensate pipe has frozen. This is an issue that can happen during the cold winter months as the condensate pipe leads outside but luckily this is an issue that can be resolved fairly quickly without the need for an engineer. You just need to thaw out the condensate pipe, which you can find out how to do with our guide.

Minstral

Initial User Checks
You are able to make some checks before calling out a service engineer.

Check you have enough fuel: check the sight gauge.
Check the fuel supply valves are open.
Check the external fire valve hasn’t tripped: press the trip button.
Is the boiler electrical supply on?
Is the control panel high limit thermostat tripped? Check and reset if needed.
Burner control box locked out: check and press the lens.
Mistral Boiler Error Codes
Fault	Possible Cause
Burner does not start	Air locks, supply lines blocked or tank vent blocked (no fuel getting into tank)
Restriction suspected / fuel supply fault	Power supply to the boiler failed, burner control box locked out, burner motor fault or pump seized
Burner fault locks out after 15 seconds	Photocell fault, restricted oil supply, combustion setting out of specification
No flame established (burner fault)	Ignition failure, oil restricted or nozzle locked
Burner fault runs but continually pulsates	Condensate trap blocked or flue system blocked
Lock-out	Losing oil in the supply suction line or oil level in tank below minimum level
Burner running but smokes	Tank topped with wrong fuel/ Air supply restricted/ Dust build up
Burner flame shuts down slowly	Balanced flue system leaking/ Combustion leaks/ Suction line drawing air into fuel
Burner fails to reach working temperature	Burner output restricted/ Low efficiency/ Control thermostat fault
Oil smells	Oil leakage at connection
No hot water	Circulating pump seized/ Programmer channel off
Flow and water temperature low	Programmer for central heating or domestic hot water are off, debris build-up or low water supply pressure
No central heating or hot water	Programmer channels are off, thermostat fault or turned off
Thermostat trips off	Fault circulating pump
No central heating	Spring fault or return valve not moving or operating properly – room stat error
No domestic hot water	Spring fault, jammed in how water mode, flow switch blocked or faulty
Discharges on pressure relief valve	Pressure vessel has lost charge, insufficient expansion volume

Potterton

Promax Combi, System, and Store Error Codes
Fault Code	Possible Cause
E10	Outdoor sensor error
E20	Central heating thermistor sensor fault
E28	Flue thermistor fault
E50	Domestic hot water sensor fault
E110	Boiler overheat tripped
E119	System pressure too low
E125	Primary water circulation fault
E130	Flue thermostat sensor tripped (lockout)
E131	Flue overheat lockout
E133	Ignition fault
E151	Printed circuit board (PCB) error
E152	PCB error
E160	Fan fault
E161	Fan fault
E164	Domestic hot water sensor error – could be a heating flow switch error)
E167	Printed circuit board (PCB) fault
E168	Printed circuit board (PCB) lockout
E193	Circulation

Potterton Promax Ultra, Gold/Titanium Combi & System Boiler Error Codes
Fault Code	Possible Cause
E10	Outdoor sensor error
E09	Gas valve wiring fault
E10	Outdoor sensor error
E15	Gas valve connection fault
E20	Central heating thermistor sensor fault
E28	Flue thermistor fault
E40	Central heating return thermistor fault
E50	Domestic hot water sensor fault
E53	Flue obstruction
E55	Calibration required
E78	Water pressure sensor fault
E83 / 84 / 85 / 86 / 87	No communication between room controller and boiler
E92	Combustion test alarm during auto-setting
E109	Poor circulation
E110	Boiler overheat tripped
E117	System pressure too high (>2.9 bar)
E118	System pressure too low
E125	Primary water circulation fault
E128	Loss of flame during operation
E129	Loss of flame during calibration
E130	Flue thermostat sensor tripped (lockout)
E133	Ignition fault
E135	Internal error
E154	Primary flow fault
E160	Fan fault
E270	Dry fire
E317	Wrong power supply (HZ)
E321	Hot water thermistor fault
E384	Flame detected when gas valve off (false flame)
E385	Low voltage (less than 195v)

Potterton Assure Combi Boiler Error Codes
Fault Code	Possible Cause
E09	Gas valve connection cable fault
E10	External probe fault
E12	Differential water flow switch is still open
E13	Differential water flow switch is still closed
E15	fault with the gas valve command
E20	Central heating NTC fault
E28	Flue NTC fault
E40	Central heating return NTC fault
E50	Domestic hot water (DHW) Negative Temperature Coefficient (NTC) sensor (tank boiler) (s.c) or DHW NTC sensor (tank boiler) (o.c.) fault
E83 / E84 / E85 / E86 / E87	Communication error
E109	Pre-circulation fault
E110	Boiler max temperature exceeded for gradient (or over temperature) – Probably a jammed pump, air in the circuit or safety thermostat sensor tripped
E118	Primary system water pressure too low
E125	Primary circulation fault
E128	Flame failure (12 times)
E129	Frequent loss of flame (safety error )
E130	Flue thermostat sensor tripped and locked out
E133	Possible gas supply issue (failure to light).
E134	Elapsed time gas valve open without gas
E135	Internal error (interruption of gas supply)
E154	Flow/return sensor temperature test
E160	Problem with fan (possible wiring fault)
E163	Domestic hot water (DHW) Negative thermistor coefficient (NTC) sensor (s.c.) or (o.c.) fault
E270	Dry fire
E317	Wrong power supply (HZ)
E321	Hot water fault
E384	False flame
E385	Under voltage
E430	Water pressure test
E430 + Flame crossed	Water pressure test failed

Ravenheat

Ravenheat Boiler Error Codes
Fault Code	System Behaviour
F73	Heating circuit pressure sensor fault
F74	Heating circuit pressure sensor fault
F76	Thermal fuse fault
F77	Fault in gas valve motor
F83	No water in the installation – the temperature does not increase when the burner is lit
F84	Permanent temperature difference betweenF flow and return heating sensors
F85	Flow and return heating sensors fault
F86	Underfloor heating contact fault
ERR	User interface fault
4	Domestic hot water (DHW) sensor faulty
Ravenheat CSI 120 Boiler Error Codes
Fault Code	System Behaviour
17	Possible issue with fan voltage
1	Boiler failed to ignite – problem with gas valve operation, fan failing to start, ignition control board and cables
28	Failed low water – pressure switch or pump, possible issue with pump, incorrect system pressure or the low water switch pressure needs replacing
12	Failed heating sensor – issue with heating sensor and could need replacing
4	Failed overheat – the overheat thermostat needs checking
30	Failed flue temperature – check operating system
31	Failed flue temperature – the flue sensor needs checking or replacing
2	Failed temperature – try resetting the boiler
Ravenheat CS 80/90, WH System, WH 80/90 Boiler Error Codes
Fault Code	System Behaviour
E02	Problem with the pump circulation
E03	Flow sensor damaged
E04	Domestic hot water (DHW) sensor damaged
E05	Problem with fan – possibly no signal
E06	Central heating (CH) sensor is overheating
E08	Low water pressure
E09	Overheat sensor overheating
E10	High water pressure
E13	Software error
E21	Central heating (CH) return sensor overheating
E22	Flue sensor overheating
E23	Flue sensor damaged
E24	Central heating return sensor error – possibly damaged
E25	Main heat exchanger frozen
E29	Domestic hot water (DHW) sensor overheating error
E31	OpenTherm communication error
E41	Different flow/return temperatures
E42	Different temperature error
E43	Different temperature error
E44	Different temperature error
E46	Water pressure sensor error – could be open or short
Ravenheat HE 80/90 HE 25-30s, HE 80-98s, HE 8-98s or HE 25-30s compact
Different temperature error

Fault Code	System Behaviour
02E	Problem with the pump circulation
03E	Flow sensor damaged
04E	Domestic hot water (DHW) sensor damaged
05E	Problem with fan, possibly no signal
06E	Central heating sensor is overheating
08E	Low water pressure
09E	Overheat sensor overheating
10E	High water pressure error
13E	Software error
21E	Central heating return sensor overheating
22E	Flue sensor overheating
23E	Flue sensor damaged
24E	Central heating return sensor error, possibly damaged
25E	Main heat exchanger frozen
29E	D.H/W sensor overheating error
31E	OpenTherm (OT) communication error
41E	Different temperature between flow and return
42E	Different temperature error
43E
44E	Different temperature error
46E	Water pressure sensor error, could be open or short

Viessmann

Vitodens 200 Boiler Error Codes
Fault Code	System Behaviour	Cause of Problem
2	Burner control switches to lockout	Safety chain was activated
04, 05, 06, 08	Burner control switches to lockout	Fan speed too high/low at start
07, 09	Burner control switches to lockout	Basic level of air pressure threshold in standby mode not correct
0A	Burner control switches to lockout	Fault with fan speed
0D	Burner control switches to lockout	Reset button pressed repeatedly or while burner is running
1A, 1B	Burner blocked	Flow sensor 1, 2 faulty
1F	Burner blocked	Differential flow rate too large
25	Boiler operates with high boiler water temperature	Emissions test switch turned to “hand symbol” for 30 minutes already
26	Boiler operates with continuous relay test	Setting mode for maximum or minimum rated input active for 30 minutes already
35	Boiler does not activate	Reset button (pressed while burner is OFF) with emissions test switch turned to “hand symbol”
A2	N/A	KM-BUS fault to Vitocom
A5	N/A	Short circuit / open circuit
Fault Code 0B
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Burner control switches to lockout, fan doesn’t idle after auto reset (incorrect fan rpm).	Severe wind conditions in vent system
Vitodens 100-W	Burner blocked	Insufficient water flow, incorrect flow direction or defective flow switch.
Fault Code 0C
Boiler Model	System Behaviour	Cause of Problem
Vitodens 100-W	Burner blocked	Insufficient power supply
Vitodens 200	Burner control switches to lockout	Flame signal still present after switching off
Fault Code 0F
Boiler Model	System Behaviour	Cause of Problem
Vitodens 222-F	Control mode	Displayed in the fault history
Vitotronic 300 / Vitotronic 300-K, with Vitotronic 300 / Vitodens 200-W / Vitocontrol-S, with Vitotronic 100	Control mode / Controlled operation	Boiler service required
Vitotronic 200 / 300	Normal operation	Boiler service required
Vitocontrol-S, MW1 with Vitotronic 100 / Vitotronic 300-K, MW1S with Vitotronic 100	Control mode	Maintenance
Fault Code 10
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200-W / 222-F / Vitotronic 300 / 200/ 200-H / 050/200-H / 300-K / vitocontrol-S	Boiler operates based on outdoor temperature of 32°F / 0°C	Short circuit – Outdoor temperature sensor
Vitotronic 300-K, MW2S with Vitotronic 100 / Vitodens 100-W (combiPLUS) / 200-w / Vitocontrol-S, WB2B with Vitotronic 100	Controls as if the outdoor temperature / Constant Mode	Outdoor temperature sensor shorted out
Viessmann Fault Code 10, 14, F3, and F4
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Burner control switches to lockout	No flame signal is present
Fault Code 18 and D1
Boiler Model	System Behaviour	Cause of Problem
Vitodens 100 / 200-W / 222-F / Vitotronic 300-K With 100 / Vitocontrol-S	Boiler operates based on outdoor temperature of 32°F / 0°C / Constant Mode	Outdoor temperature sensor cable broken
Vitotronic / 100 / 200 / 300 / 050/200-H /300-K / Vitocontrol-S, MW1 with Vitotronic 100	Operates on basis of 32°F / 0°C outdoor temperature	Open circuit – Outdoor temperature sensor
Vitotronic 200-H / Vitotronic 300-K, MW1B with Vitotronic 300 / Vitotronic 300-K, MW2B with Vitotronic 200	Controls as if the outdoor temperature	Lead break, Outdoor temperature sensor
Vitotronic 050/200-H	Activates after 0°C / 32°F outdoor temperature	Cable break – Outdoor temperature sensor
Vitodens 100-W	Burner in fault mode	DIP switch S2 is set to “ON”
Fault Code 19
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300	Activates after 0°C / 32°F outdoor temperature	Communication fault, Wireless Outdoor temperature sensor
Fault Code 20
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 / Vitotronic 300 / 300-K / 200 / 100	Stand-alone control unit without supply temperature sensor (possibly supply temperature not high enough)	short circuit – Common supply temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K, with Vitotronic 200	Vitocontrol-S, controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough)	Common supply temperature sensor shorted out
Vitocrossal 300	Regulates without supply temperature sensor (low-loss header)	Short circuit – System Flow temperature sensor
Vitodens 200-W / 222-F	Regulates without supply temperature sensor (low-loss header)	Short circuit – System supply temperature sensor
Vitotronic 050/200-H< / 200 / 200-H / 300	Mixing valve closes/ closed	Short circuit – Supply temperature sensor / mixing valve circuit M1
Vitotronic 300-K, with Vitotronic 100	Vitotronic 300-K, MW1S controls in a stand-alone manner w/o strap-on sensor (supply temperature may not be high enough)	Short circuit – Strap-on temperature sensor
Vitodens 200-W	Regulates without supply temperature sensor (low-loss header)	System supply temperature sensor shorted out
Fault Code 21
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 200 / 300	operation without influence of return water temperature	Short circuit – Return water temperature sensor
Viessmann Fault Code 28
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100	Vitocontrol-S, VD2/CT3/CM2 controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough)	Open circuit – Common supply temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K,with Vitotronic 100	Vitocontrol-S, WB2B controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough)	Common supply temperature sensor cable broken
Vitocrossal 300 / Vitodens 200-W / 22-F	Regulates without supply temperature sensor (low-loss header)	System supply temperature sensor cable broken
Vitotronic 050/200-H	Mixing valve closes	Cable break – Supply temperature sensor
Vitotronic 050/200-H	Mixing valve is closed	Open circuit – Supply temperature sensor of mixing valve circuit M1
Vitotronic 200-H / Vitotronic 200 / 300	Mixing valve is being closed	Lead break, Supply temperature sensor, heating circuit with mixing valve M1 (heating circuit 1)
Vitotronic 300 Vitotronic / 300-K with Vitotronic 300 / 200	Stand-alone control unit without supply temperature sensor (possibly supply temperature not high enough)	Lead break, Common supply temperature sensor
Vitotronic 300-K with Vitotronic 100	Vitotronic 300-K, MW1S controls in a stand-alone manner w/o strap-on sensor (supply temperature may not be high enough)	Open circuit – Strap-on temperature sensor
Fault Code 29, 41, 49, F80, F81, F83, F88 and F89
Fault Code 30
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 200 / 300	Normal operation without influence of return water temperature	Open circuit 1 or 2 – Return water temperature sensor (of mixing valve circuit 1)
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S, with Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 100 / 200 / 300	Burner is started and stopped via an adjustable high limit	Short circuit – Boiler water temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitodens 100-W (CombiPLUS)/ 200-1	Burner blocked	Boiler water temperature sensor shorted out
Fault Code 38
Boiler Model	System Behaviour	Cause of Problem
Vitodens – 200-W, 222-F and COMBIPLUS	Burner blocked	Boiler water temperature sensor cable broken
– Vitotronic 100, 200 and 300 – Vitocontrol-S with Vitotronic 100	Burner is switched on and off by the adjustable high limit	Open circuit – Boiler temperature sensor
Vitotronic 300-K with Vitotronic 300 / Vitotronic 300-K with Vitotronic 300	The burner is started and stopped via a temperature controller	Lead break, Boiler water temperature sensor
Vitodens 100-W	Burner blocked	Boiler water temperature sensor lead broken
Fault Code 40 And 44
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Mixing valve closes	Heating circuit 2 with mixing valve supply short circuit on temperature sensor
Fault Code 41
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300	Operation without accounting for return water temperature	Short circuit – Return water temperature sensor of mixing valve circuit 2
Fault Code 48 and 4C
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Mixing valve closes / Closed	Heating circuit 2 with mixing valve supply temperature sensor cable broken / open circuit
Fault Code 50, 51, 58 and 59
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200-W and 222-F	No domestic hot water (DHW) – fault with DHW	Short circuit/open circuit, DHW tank temperature sensor or lead break
Fault Code 52
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300	Control mode	Short circuit – supply temperature sensor low-loss header
Vitodens 100-W CombiPLUS	Burner blocked (with CombiPLUS only)	Flow sensor shorted out (in CombiPLUS)
Fault Code 55, 56 and 57
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300-K with Vitotronic 200	Control mode	Maintenance or error on Vitotronic 100 of boiler 5-8
Fault Code 5A, B7, and B8
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control mode	Lead break, low-loss header Supply temperature sensor
All Viessmann boilers	Burner blocked / control mode	sensor cable broken
Fault Code 5C, 5D, 5E and 5F
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300-K with Vitotronic 200	Control mode	Communication fault, Vitotronic 100 of boiler 5-8
Fault Code 60, 68, 70, 78, BD, BE and BF
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	– No output reduction – Return control Open – Boiler with maximum temperature	Short/open circuit – Temperature sensor [17A]
Fault Code 80, 81, 82, 83 and FD
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner control unit in a fault state; system cools down; burner control unit locked out	Short circuit – Boiler water temperature sensor, burner control unit
Fault Code 88, 89, and E6
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300	Burner control unit in a fault state	Lead break, Boiler water temperature sensor, burner control unit

Fault Code 8C, 8D, 8E and 8F
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 – Vitotronic 300-K with Vitotronic 100 / 200	Control mode	Communication fault, Vitotronic 100 of boiler 1-4
Fault Code 90, 91, 92, 93, 94, 98, 99, 9A, 9B , 9C, 9E, 9F and AB
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control mode	Short circuit – Temperature sensor [5] / [6] / [7] / [10]
Fault Code A0, A1, A2, AA, and AC
Boiler Model	System Behaviour	Cause of Problem
Vitotronic 300 – Vitotronic 300-K with Vitotronic 300	Boiler cools down	Fault, safety equipment at “X2 / X3 / X7” of plug-in adaptor 2 for external safety equipment
Vitodens 200	– Boiler operates in emergency mode (after approx. 30 min) BUS fault – Boiler cools down	-Internal BUS fault – Open circuit – Internal BUS connection
Fault Code A3, B0, F1, FE1 and FE2
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner blocked	Flue gas temperature sensor not properly positioned – check Sensor
Fault Code A4
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Pump runs at maximum speed	Open circuit – BUS connection with variable speed heating circuit pump
Fault Code A7
Boiler Model	System Behaviour	Cause of Problem
Vitocrossal 300 – Vitodens 200-W, 222-F, 300	Control mode (stays in factory default setting)	Faulty Programming unit
Fault Code A8
Boiler Model	System Behaviour	Cause of Problem
Vitodens 222-F	Burner blocked. The venting program is started automatically	Air lock in the Internal circulation pump or minimum flow rate not achieved
Fault Code A9, BA, BB, BC and FE0
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control Mode	Communication error
Fault Code AD
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 -Vitotronic 100 -Vitotronic 300-K with Vitotronic 300	Control mode	Isolation valve configuration error: Coding OC:2, OC:3 or OC:4 set, and coding 4E:1 not set
Fault Code B1
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control mode	Communication error – programming unit
Fault Code B2
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Boiler cools down	Sensor inputs are not read correctly
Fault Code B3 and E5
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Setting via service level not possible	Data points are not stored – internal fault VR20
Fault Code B4
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 – Vitotronic 100, 200 and 300 – Vitotronic 300-K with Vitotronic 100	Emissions test mode	Internal electronics fault
Vitocontrol-S with Vitotronic 100 / Vitodens 200-W	Regulates as if the outside temperature was 32°F (0°C)	Internal fault
Vitotronic 050/200-H	Undefined control characteristics	Internal electronics fault
Fault Code B5
System Behaviour	Cause of Problem
All Viessmann boilers	Control mode	Internal electronics fault
Fault Code B6
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Constant mode	Invalid hardware recognised
Fault Code B9, ED, F0, FE5, FEC, FED, FEE, FEF, FFD and FFF
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Normal operation / fault around burner control unit	Internal fault
Fault Code C1
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control Mode	External safety equipment
Fault Code C2-C8, CD-CF, D2-D8, DA-DF, and E0
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Control mode	Open circuit – KM BUS to solar control unit / Extension AM1 / DE1-DE3 M1 / communication fault
Fault Code C9, CA and CB
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / 300 / Vitotronic 300-K with Vitotronic 300	Boiler cools down	Error: Maximum pressure limiter 1 2
Fault Code CC and F0
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200	Burner control unit switches to lockout (due to large line voltage fluctuations)	Differential air pressure sensor / open circuit
Fault Code D4
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Boiler cools down	Fixed high limit has responded or fuse F2 has blown.
Fault Code D5
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Boiler drives up to electronic maximum limit	Boiler does not log in at the cascade control unit
Fault Code E1, E7, E8, E9, EA, EB, EC and FF2
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner in fault mode	Ionization current too high during calibration
Fault Code E2 and E3
Boiler Model	System Behaviour	Cause of Problem
Vitodens 200-W / 222-F / Vitotronic 300	Burner in fault mode	Heating water flow rate too low during calibration; flow switch caused shutdown
Fault Code E4
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner blocked	Fault, supply voltage 24V
Fault Code EE and EF
Boiler Model	System Behaviour	Cause of Problem
Vitocontrol-S with Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 300	Burner in fault mode	At burner start, flame signal is missing or too weak
Fault Code F5
Boiler Model	System Behaviour	Cause of Problem
Vitodens 100-W / 200 / 300 / Vitotronic 300	Burner blocked	Faulty Air pressure switch
Fault Code F6, 58, F9, FE1, FE2 and FF6
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Gas pressure switch shows no gas pressure / Electrical connection fault	Gas shut-off valve closed; gas pressure switch faulty; multiple problems with gas supply
Fault Code FA and FB
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner in fault mode / Emergency operation	Fan not at standstill / plug-in connection
Fault Code FB7, FF4, FF2, FF7, FF8 and FF9
Boiler Model	System Behaviour	Cause of Problem
Vitocrossal 200	Case A: Burner control unit in a fault state; system cools down; burner control unit locked out. Case B: Type of coding card	Case A: Coding card not inserted in the burner control unit; incorrect or faulty coding card. Case B: Coding card does not match burner control unit.
Fault Code FC
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner in fault mode	Gas valve faulty, issue with modulation valve control or vent system blocked
Fault Code FE
Boiler Model	System Behaviour	Cause of Problem
All Viessmann boilers	Burner blocked or in fault mode	Strong interference (EMC) field nearby, or faulty main printed circuit board (PCB)
Fault Code FE4
Boiler Model	System Behaviour	Cause of Problem
Vitocrossal 200	Burner shuts down	Multiple detection of undervoltage
Fault Code FFA, FFB and FR
Boiler Model	System Behaviour	Cause of Problem
Vitocrossal 200 / 400-620 / 186-311	Fan runs without demand; burner control unit in a fault state	Fan has not stopped, cable [100A] faulty, fan faulty, burner control unit faulty
Viessmann Error Code F4 EE
Viessmann error code F4 EE means that the condensate pipe has frozen and needs to be thawed. You can thaw out the pipe yourself fairly quickly and easily without the need for an engineer (if you feel confident enough), find out how with our guide to thawing out a frozen condensate pipe.

Vokera

Fault Code	Fault Image	System Behaviour
_St	N/A	Autostop
_CL	N/A	Call for service
A01		Ignition failure flame not sensed – internal fault
A02		Limit thermostat fault
A03		Fan fault
A04		Insufficient system water pressure
A06		Domestic how water (DHW) thermistor fault
A07		Primary flow thermistor fault – temperature of water is too high.
A08		Return thermistor fault – water temperature too high.
A09		Flue thermistor or ﬂue thermistor counter fault.
A11		False flame
A77		Low temperature thermostat fault
ADJ	N/A	Calibration
ACO		Service operation
N/A		Flame on

Fault Code	System Behaviour
P	Preheating function active
P Blinking	Preheating function running
Hours	Stand-by
—	Off
01	Failure to ignite
02	Overheat
03	Problem with fan/flue
04	Insufficient water pressure
05	Reset as described for code 01
06	Hot water thermistor open circuit
07	Primary thermistor open circuit

Vokera Mynute Boiler Error Codes

Fault Code	System Behaviour
AL10, AL20, AL21, AL26, AL28, AL34	Try resetting the boiler, if the fault reoccurs you need to contact a heating engineer.
AL40	Check the system’s pressure and refill if necessary. Reset the boiler, if the fault reoccurs then you need to contact a heating engineer.
AL41	Check system pressure – refill if necessary. If fault reoccurs, contact a heating engineer.
AL52, AL55, AL60, AL71,AL73, AL74, AL79	Contact a heating engineer.
AL74, AL79	Reset the boiler. If the fault reoccurs, contact a heating engineer.

Evolve Combi Evolve System Error Codes

Fault Code	System Behaviour
E10	Flame lockout
E011	Extraneous flame
E020	Limit thermostat
E030	Fan fault
E040	Water transducer – check system water pressure
E041	Water transducer – check system water pressure
E042	Water transducer fault
E060	Domestic hot water probe fault
4070	Fault flow sensor over temperature – flow sensor flow/return line probe differential alarm
E077	Main zone water thermostat
E080	Error with return line probe – over temperature outlet or differential alarm
E090	Flue gases over temperature probe
E091	Clean primary heat exchanger
—	Water pressure low
—	Water pressure high
—	Boiler board communication lost
—	BUS 485 communication lost
E021, E022, E023, E024, E067. E088, E097	Iono alarm
E085, E094, E095	Combustion fault/high CO
E058	Main voltage error
E065	Current modulation alarm
E086	Obstruction fumes alarm

If any of the above error codes keep appearing on your Vokera boiler, contact a professional heating engineer to find the fault and repair your boiler.

Vokera Boiler Red Light On

Vokera boilers without a digital display won’t have an error code to let you know what’s wrong with the boiler, however, they do have red and green lights that will either remain on constantly or begin flashing depending on the situation. Read our guide to the Vokera boiler red light on Boiler Guide to get your boiler back up and running.

Warmflow

Warmflow Boiler Error Codes
Fault Code	System Behaviour
E01	No flame – flame has failed during startup.
E02	Safety thermostat tripped (95°C)
E03	Flue thermo-fuse tripped
H20	Low system pressure
E05	Heating sensor fault
E22	Fan fault
E16	Parameter programming request
E35	Ionisation electrode fault
E42	Fan printed circuit board (PCB) fault

Warmhaus

Enerwa and Priwa Error Codes
Fault Code	Possible Cause
rE 02	Low water pressure in heating system – parameter is adjusted wrong
E 03	High water pressure due to excessive water pressure or safety valve error
E 04	Domestic hot water (DHW) temperature sensor failure – possible error with electronic card or the NTC sensor.
E 05	Temperature sensor from radiator error – electronic card detecting a failure.
E 13	Exhaust gas temperature sensor error – excessive temperature alarm.
E 14	Exhaust gas temperature sensor error – electronic card detecting an anomaly in the gas exhaust gas sensor.
E 15	Fan error – a fan being blocked or excessive external air pressure.
rE 06 / rE 08	No ignition – control gas supply line valves could be open
rE 07	Safety thermostat intervention from dual sensor – excessive heating occurring due to any failure during normal operation, try resetting the boiler.
E 10	AUX output sensor error
E 16	AUX return sensor failure
E 11	Gas valve modulator connection is broken – could be due to an internal failure.
E 17 / E 19	Maximum difference failure between 2 NTC temperature sensor – poor circulation.
rE 28	Maximum locking number reached – boiler has reached the maximum reset number (5 times in an hour) – attempt 1 reset each hour thereafter.
E 37	Low voltage error – voltage required for operation is too low.
E 40	Electricity network frequency error – fluctuation in electricity frequency.
rE 41	Flame loss after 6 successive ignitions – gas supply line valve being open.
E 42	Error with pushbutton
E 43	Room thermostat communication error – disconnection or communication loss in room thermostat.
rE 44	Gas valve error due to opening period without flame – try resetting the boiler.
E 62	Calibration request – boiler has detected an absence of calibration control.
rE 72	Delta T error – boiler failing to ignite. Could be due to a gas line valve being closed or a flue error.
E 74	Temperature sensor error.
E 77	Current values reached – check combustion values and CO2 calibration, try resetting the boiler if this fails. Either the board or the valve will need replacing.
E 78	Regulation current value has been reached. Try resetting the boiler, check the gas pressure and check the combustion values and CO2 calibration – if this doesn’t work the board or valve needs replacing.
E 79	Minimum regulation current reached – try resetting the boiler – checking the gas pressure and checking the combustion values and CO2 calibration – the board or valve might need replacing.
rE 80	Gas valve driver error – due to an internal failure.
rE 81	Ignition problem at the first start – this could be due the flue line, possible flue blockage or chimney gasket.
rE 82	Burning problem – due to the flue line either being blocked or chimney gasket.
E 83	Temporary mis-burning error – could be due to a gas pressure or flue line issue.
E 84	Capacity reduction for detected low gas inlet pressure – check the CO2 calibration values.
rE 88	Error in gas line cycle – possible gas valve component error.
E 89	Problem on combustion feedback signal – gas pressure needs checking.
E 90	Error in regulating combustion – possible error with the calibration values chimney gas valve and board.
E 92	Air compensation active – the CO2 values need checking, possible error with the wind presence.
E 93	Unable to regulate combustion – possible calibration value issue, chimney gas valve or board.
E 94	Low gas pressure or exhaust recirculation that could be an issue with gas pressure.
E 95	Intermittent combustion value caused by a possible error with electrode position or electrical connection stability.
E 96	Flue blockage – due to chimney and combustion values – the boiler may need a calibration.
rE 80	Gas valve error – possible internal error.
rE 81	Ignition problem at the first start – could be due to a problem with a flue line.
rE 82	Burning problem error – flue line error.
E 83	Temporary mis-burning error that may be caused by the gas pressure or flue line.

rE 88	Gas line cycle error – could be due to a gas valve component error.
rE 98	Electronic card start error.
rE 99	An error has been detected in the Combi, try resetting the boiler.

A Comprehensive list of Error Codes for your Boiler