|Possible solution / cause
|Heat exchanger sensor needs replacing.
|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.
|Temperature too high during domestic hot water (DHW) demand
|The wiring of DHW sensor needs checking, possible breakage.
|Flue gas temperature too high
|Heat exchanger needs checking for contamination.
|No flame during startup
|Gas valve is closed. Condensation drain is blocked and ignition needs checking.
|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.
|Flame simulation error
|Gas valve could need replacing or burner controller could need replacing.
|No or insufficient ionisation flow
|Wiring of ionisation/ignition pin could have a breakage shut down and could need replacing.
|Fan speed incorrect
|Fan cable needs checking, fan or burner controller could need replacing.
|Bunner controller has internal fault
|Burner controller needs replacing.
|Possible issue with heat exchanger sensor, breakage or not connected properly.
|Sensor 5 fault
|Wiring for flue gas sensor needs checking, possible breakage.
|Mounting fault sensor
|Heat exchanger sensor is not mounted correctly and needs to be mounted properly.
|Mounting fault sensor S1
|Central heating flow sensor is not mounted correctly and needs mounting properly.
|Mounting fault S3
|Domestic hot water sensor is not mounted correctly and needs mounting properly.
|Flue and / or air supply duct is blocked
|The flue and/or air supply duct could need cleaning.
|Check the BMM wiring for breakages / BMM wiring could need replacing.
|Short circuit of outdoor sensor
|Outdoor sensor could have a wiring issue, check and replace the outdoor sensor.
|The reset button needs checking for unintentional operation e.g. cleaning of control panel. Burner controller might need replacing.
|Gas valve error
|Gas valve needs checking for leakage / burner controller could need replacing
|Sensor S3 fault
|Check wiring of domestic hot water sensor for breakage or shutdown domestic hot water sensor – it could need replacing.
|Sensor fault S1
|Check wiring of central heating flow sensor for breakage and shutdown. Check that weather central heating flow sensor is connected correctly.