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Baxi Boiler Fault Codes

Kentish Plumbers are here to help.

We know it's frustrating when your boiler displays an error code, which is why we've listed some common boiler error codes below. If you're still stuck, do give us a call on 01892 489771 or click here to email us and one of our team will be able to assist.

Baxi Boiler
Error Codes Possible Fault
H.01 – .00 Temporary Fault – Temporary loss of communication between gas valve and boiler board. Fault in air/gas unit.

Loose connection to gas valve.
H.01 – .05 Temporary Fault – Maximum difference between the flow and return temperature exceeded. Non-existent or insufficient circulation. Sensor error.
H.01 – .08 Temporary Fault – Flow temperature increasing too fast in heating mode. Non-existent or insufficient circulation.
Sensor error.
H.01 – .14 Temporary Fault – Maximum flow temperature value exceeded. Non-existent or insufficient circulation. Non-existent or insufficient circulation.
H.01 – .18 Temporary Fault – No circulation of water. Non-existent or insufficient circulation. Sensor error.
H.01 – .21 Temporary Fault – Flow temperature increasing too fast in DHW mode. Non-existent or insufficient circulation. Sensor error.
H.02 – .02 Temporary Fault – No input of parameters C1/C2. PCB not configured.
H.02 – .03 Temporary Fault- Incorrect configuration settings C1/C2.
H.02 – .04 Temporary Fault – Parameter error. Incorrect parameters.
H.02 – .06 Temporary Fault – System water pressure. Water leak on boiler. Water leak on system.
H.03 -.00 Temporary Fault – Communication error with NTC flue sensor. Sensor not, or badly connected. Bad connection. Sensor fault.
H.03 -.01 Temporary Fault – Communication error with the HMI PCB. HMI not connected.
H.03 -.02 Temporary Fault – No flame during operation. No ionization current.
E.00 – .04 Permanent Fault – Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.00 – .05 Permanent Fault – Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.01 – .02 Permanent Fault – Temperature measured by return sensor greater than flow sensor. Bad connection. Sensor fault. Sensor not or badly connected.
E.01 – .04 Permanent Fault – Loss of flame detected 5 times in 24 hours (With burner on). No ionization current.
E.01 – .11 Permanent Fault Requiring Reset – Incorrect fan speed. External draught over the boiler. Defective gas/air unit.
E.01 – .12 Permanent Fault Requiring Reset – Temperature measured by return sensor greater than flow temperature.
E.01 – .17 Permanent Fault Requiring Reset – No circulation. Sensor not or badly connected. Sensor fault.
E.01 – .20 Permanent Fault – Maximum flue gas temperature value reached (>140 Deg C). No circulation. Sensor fault.
E.02 – .00 Permanent Fault – Boiler reset in progress. Reset button has been pressed.
E.02 – .07 No or low system water pressure. Low system pressure (less than 0.5bar) boiler will not function.
E.02 – .16 Permanent Fault – On board CSU time-out. Check PCB for damage.
E.02 – .17 Permanent Fault – Permanent loss of communication between gas valve and boiler PCB. Fault in air/gas unit. Loose connection to gas valve.
E.02 – .19 Permanent Fault – Jumper 1 changed. Check position of jumper 1.
E.02 – .20 Permanent Fault – Jumper 2 changed. Check position of jumper 2.
E.02 – .21 Permanent Fault – Jumper 3 changed. Check position of jumper 3.
E.02 – .47 Permanent Fault – Connection to external device unsuccessful. Check wiring to external device.
E.02 – .48 Permanent Fault – Configuration to external device unsuccessful. Check pairing to external.
E.04 – .00 Permanent Fault – Gas valve fault. Gas valve not detected.
E.04 – .01 Permanent Fault – Flow temperature sensor short-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .02 Permanent Fault – Flow temperature sensor open-circuited. Sensor not or badly connected. Bad connection. 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. Sensor fault.
E.04 – .05 Permanent Fault – Flue temperature sensor open-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .06 Permanent Fault – Critical flue gas temperature value reached. No circulation. 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. 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. Ionization current present even though there is no flame. The burner remains very hot (CO2 too high). Defective gas/air unit.
E.04 – .13 Permanent Fault – Fan rotor blocked. Fan seized. Wiring to fan damaged.
E.04 – .17 Permanent Fault – Problem with gas valve. Defective gas/air unit.
Error Code Possible Fault
E20 Central heating NTC fault
E28 Flue NTC fault, air pressue 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 or flame failure
E160 Fan or fan wiring Fault
E193 Pre-circulation fault
Error Code Possible Fault
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 DHW NTC 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 i) Boiler max temperature exceeded for gradient (probable pump jammed or air in the circuit). OR ii) Boiler max temperature exceeded for overtemperature (probable pump jammed or air in the circuit). OR iii) 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 NTC sensor fault (s.c.) OR Domestic Hot Water 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.
Error Code Possible Fault
1 flash green Maximum flow temperature exceeded, Flow temperature rise rate too high, Excessive difference between, flow and return temperature
2 flashes green BL terminals on User Interaction, Controller are open circuit
3 flashes green No flame detected during operation
4 flashes green Bad connection or wiring fault, Internal communication fault
5 flashes green Parameter error or faulty PU, Configuration error or PCB fault
6 flashes green possible fault Internal fault in combustion control unit
1 flash red Bad connection to flow or return temperature sensor
2 flashes red Over-temperature thermostat on heat exchanger activated, No water flow through heat exchanger, PCB over-temperature condition, Flue fault resulting in, Recirculation or activation of airpressure switch (if fitted)
3 flashes red No ignition, No flame detected following ignition, False flame signal detected
4 flashes red Fan calibration error, Fan failure
5 flashes red Bad connection to PU, Parameter error or faulty PU
6 flashes red possible fault Bad connection or wiring fault, Parameter error
Error Code Possible Fault
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
E109 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)
E135 Interruption of gas supply (internal error)
E154 Flow/ return sensor temperature test
E160 Fan or fan wiring fault
E270 Circulation fault (Dry fire)
E321 Hot water NTC fault
E384 False flame
Error Code Possible Fault
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 Low (<0.5 bar)
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 Fan Fault
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)
Error Code Possible Fault
1 Green flash Boiler temp reached
3 Green flashes Temporary Flame Loss
4 Green flashes Communication error between PCB and Control
5 Green flashes Parameter Error On PSU/PCB
6 Green flashes Miscellaneous Error
1 Red flash Sensor Error; Sensor Fault, 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 or PSU Error
6 Red flashes Miscellaneous
Error Code Possible Fault
E10 Outdoor sensor error
E20 Central Heating Thermistor Senor Fault
E28 Flue Thermistor Fault
E110 Boiler Overheat
E119 Low water pressure
E125 Primary Water Circulation Fault
E131 Flue overheat lock out
E133 Ignition fault
E160/E161 Fan Fault
E164 Fan Fault
E167 PCB Fault
E168 PCB lock out
E193 Circulation fault
Error Code Possible Fault
Flash Flash On Fan Fault
Flash Off Flash Incoming Voltage less then 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
Error Code Possible Fault
E4 Ignition failure
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)
Error Code Possible Fault
E0 Temperature sensor fault
E1 Boiler overheat tripped
E2 Poor circulation
E3 PCB fault
E4 Ignition failure
E10 Poor/No circulation
E12 PCB Fault
E13 Heat exchanger thermal fuse tripped
E83/84/85/86/87 Fan fault normally E8
Error Code Possible Fault
1 Green Flash Boiler temp reached
3 Green Flashes Boiler temp reached
3 Green Flashes Temporary Flame Loss
4 Green Flashes Communication error between PCB and Control
5 Green Flashes Parameter Error On PSU/PCB
6 Green Flashes Miscellaneous Error
1 Red Flash Sensor Error; Sensor Fault, 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 or PSU Error
6 Red Flashes Miscellaneous