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.