Baxi Baxi 200 & 400

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.


Error code Possible faultInstaller action
H.01 - .00Temporary Fault - Temporary loss of communication between gas valve and boiler board.
Fault in air/gas unit.
Loose connection to gas valve.
Replace air gas unit.
Check gas valve connectionfrom PCB.
H.01 - .05Temporary Fault - Maximum difference between the flow and return temperature exceeded.Non-existent or insufficient circulation. Sensor error.Check circulation.?Check water pressure.?Check sensors are operating correctly.?Check that the sensor has been correctly fitted.?Check the cleanliness of the heat exchanger.
H.01 - .08Temporary Fault - Flow temperature increasing too fast in heating mode.
Non-existent or insufficient circulation. Sensor error
Check circulation.
Check water pressure.
Check sensors are operating correctly.
Check that the sensor has been correctly fitted.
Check the cleanliness of the heat exchanger.
H.01 - .14Temporary Fault - Maximum flow temperature value exceeded.
Non-existent or insufficient circulation.
Non-existent or insufficient circulation.
Check circulation.
H.01 - .18Temporary Fault - No circulation of water.
Non-existent or insufficient circulation. Sensor error.
Check circulation.
Check water pressure.
Check sensors are operating correctly.
Check that the sensor has been correctly fitted.
Check the cleanliness of the heat exchanger.
Check pump.
H.01 - .21Temporary Fault - Flow temperature increasing too fast in DHW mode.
Non-existent or insufficient circulation. Sensor error.
Check circulation.
Check water pressure.
Check sensors are operating correctly.
Check that the sensor has been correctly fitted.
Check the cleanliness of the heat exchanger.
H.02 - .02Temporary Fault - No input of parameters C1/C2. PCB not configuerd.Input C1/C2.
H.02 - .03Temporary Fault- Incorrect configuration settings C1/C2.Reset C1/C2.
H.02 - .04Temporary Fault - Parameter error. Incorrect parameters.Reset C1/C2.
H.02 - .06Temporary Fault - System water pressure.
Water leak on boiler.
Water leak on system.
Check boiler.
Check system.
Repressurise system.
H.03 - .00Temporary Fault - Communication error with NTC flue sensor.
Sensor not, or badly connected.
Bad connection.
Sensor fault.
Check wiring.
Check sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary
H.03 - .01Temporary Fault - Communication error with the HMI PCB. HMI not connected.Check wiring.
H.03 - .02Temporary Fault - No flame during operation. No ionization current.Purge gas supply to remove air.
Check gas valve is fully opened.
Check supply pressure.
Check operation and setting of the gas valve unit.
Check air inlet and flue gas discharge flues are not blocked.
Check that there is no recirculation of flue gases.
E.00 - .04Permanent Fault - Return temperature sensor open-circuit.
Sensor not or badly connected.
Bad connection.
Sensor fault.
Check the wiring.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.00 - .05Permanent Fault - Return temperature sensor short-circuit.
Sensor not or badly connected.
Bad connection. Sensor fault.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.01 - .02Permanent Fault - Temperature measured by return sensor greater than flow sensor.
Bad connection. Sensor fault. Sensor not or badly connected
Water circulation direction reversed. Flow and return pipes reversed.
Replace the sensor if necessary.
Check the circulation (direction, pump, valves).
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Check pipework configuration.
E.01 - .04Permanent Fault - Loss of flame detected 5 times in 24 hours (With burner on). No ionization current.Purge the gas supply to remove air.
Check that the gas valve is fully opened.
Check the supply pressure.
Check the operation and setting of the gas valve unit.
Check that the air inlet and flue gas discharge flues are not blocked.
Check that there is no recirculation of flue gases.
E.01 - .11Permanent Fault Requiring Reset - Incorrect fan speed.
External draught over the boiler. Defective gas/air unit..
Check for adequate draw on the chimney connection.
Check the gas/air unit and replace if necessary.
E.01 - .12Permanent Fault Requiring Reset - Temperature measured by return sensor greater than flow temperature.Check sensors
E.01 - .17Permanent Fault Requiring Reset - No circulation. Sensor not or badly connected. Sensor fault.Vent the air in the heating system.
Check the water pressure.
Check the wiring.
Check the circulation (direction, pump, valves).
Check the cleanliness of the heat exchanger.
Check that the sensors are operating correctly.
Check that the sensor has been.correctly fitted.
Replace the sensor if necessary.
E.01 - .20Permanent Fault - Maximum flue gas temperature value reached (>140 Deg C).
No circulation. Sensor fault..
Vent the air in the heating system.
Check the water pressure.
Check the wiring.
Check the circulation (direction, pump, valves).
Check the cleanliness of the heat exchanger.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.02 - .00Permanent Fault - Boiler reset in progress. Reset button has been pressed.Boiler carrying out reset (Information only).
E.02 - .07Permanent Fault - Low system water pressure.
Water leak on boiler.
Water leak on system.
Check boiler.
Check system.
Repressurise system.
E.02 - .16Permanent Fault - On board CSU time-out. Check PCB for damage.Replace the PCB if necessary.
E.02 - .17Permanent Fault - Permanent loss of communication between gas valve and boiler PCB.
Fault in air/gas unit. Loose connection to gas valve.
Replace air/gas unit.
Check gas valve connection from PCB.
E.02 - .19Permanent Fault - Jumper 1 changed.
Check position of jumper 1.
Put jumper 1 to the off position.
E.02 - .20Permanent Fault - Jumper 2 changed.
Check position of jumper 2.
Put jumper 2 to the off position.
E.02 - .21Permanent Fault - Jumper 3 changed.
Check position of jumper 3..
Put jumper 3 to the off position.
E.02 - .47Permanent Fault - Connection to external device unsuccessful.
Check wiring to external device.
Check wiring.
E.02 - .48Permanent Fault - Configuration to external device unsuccessful.
Check pairing to external.
Pair the devices.
E.04 - .00Permanent Fault - Gas valve fault. Gas valve not detected.Check the wiring.
Check resistance across gas valve terminals.
Replace gas valve if necessary.
E.04 - .01Permanent Fault - Flow temperature sensor short-circuited.
Sensor not or badly connected.
Bad connection.
Sensor fault.
Check the wiring.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.04 - .02Permanent Fault - Flow temperature sensor open-circuited.
Sensor not or badly connected.
Bad connection.
Sensor fault.
Check the wiring.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.04 - .03Permanent Fault - Critical flow temperature reached.
Non-existent or insufficient circulation.
Check circulation.
E.04 - .04Permanent Fault - Flue temperature sensor short-circuited.
Sensor not or badly connected.
Bad connection.
Sensor fault.
Check the wiring.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.04 - .05Permanent Fault - Flow temperature sensor open-circuited.
Sensor not or badly connected.
Bad connection.
Sensor fault..
Check the wiring.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.04 - .06Permanent Fault - Critical flue gas temperature value reached.
No circulation.
Sensor fault.
Vent the air in the heating system.
Check the water pressure.
Check the wiring.
Check the circulation (direction, pump, valves).
Check the cleanliness of the heat exchanger.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary
E.04 - .08Permanent Fault - Maximum safe temperature value reached.
(Safety thermostat open-circuited).
No circulation.
Sensor not or badly connected.
Bad connection.
Sensor fault.
Vent the air in the heating system.
Check the water pressure.
Check the wiring.
Check the circulation (direction, pump, valves).
Check the cleanliness of the heat exchanger.
Check that the sensors are operating correctly.
Check that the sensor has been correctly fitted.
Replace the sensor if necessary.
E.04 - .10Permanent Fault - Five burner start-up failures.If no ignition: Check cabling of ignition transformer.
Replace the ionization/ignition electrode.
Check the breakdown to earth.
Check the condition of the burner set.
Check the earthing.
Defective gas/air unit.
If ignition arc but not flame formation: Check that the gas valve is fully opened.
Check the supply pressure.
Purge the gas supply to remove air.
Check the operation and setting of the gas valve unit.
Check that the air inlet and flue gas discharge flues are not blocked.
Check the wiring on the gas valve.
Defective gas/air unit.
If presence of flame but insufficient ionization (<1_A): Check that the gas valve is fully opened.
Check the supply pressure.
Replace the ionization/ignition electrode.
Check the earthing.
Check the wiring on the ionization/ignition electrode.
E.04 - .12Permanent 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.
Press the RESET button for 5 seconds.
Replace the ionization/ignition electrode.
Set the CO2.
Check the gas/air unit and replace if necessary.
E.04 - .13Permanent Fault - Fan rotor blocked. Fan seized. Wiring to fan damaged.Replace air/gas unit.
E.04 - .17Permanent Fault - Problem with gas valve. Defective gas/air unit.Replace air/gas unit

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