Baxi Boiler Issues: Errors and Fault Codes

When your Baxi boiler develops a problem it will display a fault code to help you understand what went wrong. Error messages and fault codes also help your engineer to identify issues and determine the steps that need to be taken to rectify any problems with your boiler. Whilst some fault codes can be cleared by simply pushing the reset button, the majority will require the attention of a qualified engineer.

To find out what a Baxi boiler fault code means, you can consult your boiler manual or scroll through the tables below.

Baxi 200 Combi and Baxi 400 Combi Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
H.01 – .00 Temporary loss of communication between gas valve and boiler board. Fault in the air/gas unit. Loose connection to gas valve.
H.01 – .05 Maximum difference between the flow and return temperature exceeded. Non-existent or insufficient circulation. Sensor error.
H.01 – 08 Flow temperature increasing too fast in heating mode. Non-existent or insufficient circulation. Sensor error.
H.01 – .14 Maximum flow temperature valve exceeded. Non-existent or insufficient circulation.
H.01 – .18 No circulation of water. Non-existent or insufficient circulation. Sensor error.
H.01 – .21 Flow temperature increasing too fast in Domestic Hot Water (DHW) mode. Non-existent or insufficient circulation. Sensor error.
H.02 – .02 No input of parameters C1/C2. PCB not configured.
H.02 – .03 Incorrect configuration settings C1/C2.
H.02 – .04 Parameter error. Incorrect parameters.
H.02 – .06 Temporary fault with system water pressure. Water leak on boiler. Water leak on system.
H.03 – .00 Communication error with NTC flue sensor. Sensor not or badly connected. Bad connection or sensor fault.
H.03 – .01 Communication error with the HMI PCB. HMI not connected.
H.03 – .02 No flame during operation. No ionization current.
E.00 – .04 Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection or sensor fault.
E.00 – .05 Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection or sensor fault.
E.01 – .02 Temperature measured by return sensor is greater than flow sensor. Bad connection. Sensor not or badly connected. Sensor fault.
E.01 – .04 Loss of flame detected 5 times in 24 hours with burner on. No ionization current.
E.01 – .11 Permanent fault that requires a reset. Incorrect fan speed. External draught over boiler. Defective gas/air unit.
E.01 – .12 Permanent fault that requires a reset. Temperature measured by return sensor is greater than flow temperature.
E.01 – .17 Permanent fault that requires a reset. No circulation. Sensor not or badly connected. Sensor fault.
E.01 – .20 Maximum flue gas temperature valve reached. No circulation. Sensor fault.
E.02 – .00 Boiler reset in progress. Reset button has been pressed.
E.02 – .07 No or low system water pressure. Low system pressure less than 0.5 bar boiler will not function.
E.02 – .16 Permanent fault. On board CSU time-out – check PCB for damage.
E.02 – .17 Permanent loss of communication between gas valve and boiler PCB. Fault in air/gas unit. Loose connection to gas valve.
E.02 – .19 Jumper 1 changed – check position of jumper 1.
E.02 – .02 Jumper 2 changed – check position of jumper 2.
E.02 – .21 Jumper 3 changed – check position of jumper 3.
E.02 – .47 Unsuccessful connection to external device. Check external device wiring.
E.02 – .48 Unsuccessful configuration to external device. Check pairing to external.
E.04 – .00 Gas valve fault – gas valve not detected.
E.04 – .01 Flow temperature sensor has short-circuited. Sensor not or badly connected. Bad connection or sensor fault.
E.04 – .02 Flow temperature sensor open-circuited. Sensor not or badly connected. Bad connection or sensor fault.
E.04 – .03 Critical flow temperature reached. Non-existent or insufficient circulation.
E.04 – .04 Flue temperature sensor has short-circuited. Sensor not or badly connected. Bad connection or sensor fault.
E.04 – .05 Flue temperature sensor open-circuited. Sensor not or badly connected. Bad connection or sensor fault.
E.04 – .06 Critical flue gas temperature valve reached. No circulation or sensor fault.
E.04 – .08 Maximum safe temperature 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 an issue with the gas supply.
E.04 – .12 False flame signal. Short-term fluctuation of the mains. Ionization current present even though there is no flame. The burner remains very hot. Defective gas/air unit.
E.04 – .13 Fan rotor blocked, fan seized or damage to fan wiring.
E.04 – .17 Issue with gas valve. Defective gas/air unit.

Baxi 600 Combi and Baxi 800 Combi Boiler Fault Codes

FAULT CODE DESCRIPTION / 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 NTC fault.
E28 Flue NTC fault.
E40 Central heating return NTC fault.
E50 Domestic hot water (DHW) sensor fault (tank boiler) (s.c.) or DHW NTC sensor fault (tank boiler) (o.c.).
E83, E84, E85, E86 and E87 No communication.
E109 Pre-circulation fault.
E110 Boiler maximum temperature exceeded for gradient (pump may have jammed or there is air in circuit) or boiler maximum temperature exceeded for overtemperature (pump may have jammed or there is air in the circuit) or the safety thermostat sensor has tripped.
E118 Primary system water pressure is too low.
E125 Circulation fault (primary).
E128 Frequent flame failure (12 times).
E129 Safety error for frequent loss of flame with maximum correction during the ignition during calibration function.
E130 Flue thermostat sensor has tripped (lockout).
E133 Failure to light – could be an issue with the gas supply.
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 Fault with fan or fan wiring.
E163 Domestic hot water (DHW) NTC 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 NTC fault.
E384 False flame.
E385 Under voltage.
E430 Water pressure temporary test.
E430 & flame crossed Water pressure test failed.

Baxi Platinum+ 40KW Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
E20 Central heating NTC fault.
E28 Flue NTC fault, air pressure switch fault, blocked flue, blocked condensate or wiring fault.
E50 Hot water NTC fault.
E110 E110 safety thermostat operated.
E119 Water pressure switch not operated.
E125 Circulation fault (primary circuit).
E130 Flue NTC operated.
E133 Interruption of gas supply of flame failure.
E160 Fault with fan or fan wiring.
E193 Pre-circulation fault.

Baxi 600 System, Baxi 800 System and Baxi 600 LPG Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
E09 Gas valve connection cable.
E15 Gas valve fault.
E20 Central heating NTC fault.
E28 Flue NTC fault.
E40 Central heating return NTC fault.
E83 Communication error.
E190 Pre-circulation fault.
E110 Safety thermostat operated.
E118 Primary system water pressure too low.
E125 Circulation fault (primary).
E128 Flame failure.
E130 Flue NTC operated.
E133 Interruption of gas supply or flame failure.
E135 Interruption of gas supply (internal error).
E154 Flow/return sensor temperature test.
E160 Fault with fan or fan wiring.
E270 Circulation fault (dry fire).
E321 Hot water NTC fault.
E384 False flame.

Baxi 600 Heat and Main Eco Compact Heat Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
1 GREEN FLASH Maximum flow temperature exceeded, flow temperature rise rate too high or excessive difference between flow and return temperature.
2 GREEN FLASHES BL terminals on User Interaction Controller are open circuit.
3 GREEN FLASHES No flame detected during operation.
4 GREEN FLASHES Bad connection, wiring fault or internal communication fault.
5 GREEN FLASHES Parameter error, faulty PU. Configuration error or PCB fault.
6 GREEN FLASHES Possible internal fault with combustion control unit.
1 RED FLASH Bad connection to flow or return temperature sensor.
2 RED FLASHES Over-temperature thermostat on heat exchanger activated, no water flow through heat exchanger, PCB over-temperature condition or flue fault resulting in recirculation or activation of air pressure switch (if fitted).
3 RED FLASHES No ignition, no flame detected following ignition or false flame signal detected.
4 RED FLASHES Fan failure or fan calibration error.
5 RED FLASHES Bad connection to PU, parameter error or faulty PU.
6 RED FLASHES Bad connection, wiring fault or parameter error.

Baxi EcoBlue Combi and System Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
E10 Outdoor sensor error.
E20 Central heating thermistor sensor fault.
E28 Flue thermistor fault.
E54 HW flow sensor fault.
E78 Water pressure sensor fault.
E100 Internal clock time error on PCB.
E109 Poor circulation.
110 Overheat.
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 protection temperature not reached.
128 Loss of flame during operation.
133 Safety time to establish flame exceeded.
153 Forced reset unit unlocked.
160 Fault with fan.
162 Air pressure switch error.
164 Heating flow switch error (Ireland) – Pressure sensor error (UK).
166 Air pressure switch fault.
270 Dry fire.
432 Earth connector error.
433 Heat exchanger temperature exceeded greater than 95 degrees.

Baxi EcoBlue Heat Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
1 GREEN FLASH Boiler temperature reached.
3 GREEN FLASHES Temporary flame loss.
4 GREEN FLASHES Communication error between PCB and control.
5 GREEN FLASHES Parameter error in PSU/PCB.
6 GREEN FLASHES Miscellaneous error.
1 RED FLASH Sensor error, temperature fault or flow fault.
2 RED FLASHES Boiler overheat has tripped.
3 RED FLASHES Ignition fault. Boiler has tried to light 5 times and failed.
4 RED FLASHES Fault with the fan.
5 RED FLASHES Parameter or PSU fault.
6 RED FLASHES Miscellaneous error.

Baxi Duo-tec and Baxi Megaflo Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
E10 Outdoor sensor error.
E20 Central heating thermistor sensor fault.
E28 Flue thermistor fault.
E110 Boiler overheat.
E119 Low water pressure.
E125 Primary water circulation fault.
E131 Flue overheat lockout.
E160, E161 and E164 Fault with the fan.
E167 PCB fault.
E168 PCB lockout.
E193 Circulation fault.

Baxi Solo Heat Boiler Fault Codes

FAULT CODE DESCRIPTION / POSSIBLE CAUSE
FLASH FLASH ON Fan fault.
FLASH OFF FLASH Incoming voltage less than 180V.
FLASH OFF ON Overheat lockout.
FLASH ON FLASH PCB fault.
FLASH ON ON PCB fault.
OFF OFF OFF No power supply.
ON FLASH FLASH No circulation/dry fire.
ON FLASH ON Thermistor fault.
ON OFF FLASH Live and neutral reversed.
ON OFF ON Ignition lockout.
ON OFF FLASH PCB fault.
ON OFF FLASH Low voltage wiring harness fault.