Select a fault code

The boiler is indicating that its annual service is due. This is not a fault but a maintenance reminder.

The boiler is in air-purge mode, removing air from the system. This is normal during initial start-up or after refilling.

Fan speed is too high or too low for safe combustion.

A fault has been detected on the gas valve. Gas flow to the burner cannot be safely controlled.

A fault in the external controls wiring — often the room thermostat or programmer circuit.

Fan or flue system fault detected. The boiler cannot safely vent combustion gases.

The flow NTC temperature sensor has failed or is reading incorrectly.

The boiler has overheated and the high limit thermostat has cut it out. Often caused by a blocked heat exchanger or poor water circulation.

Safety thermostat has activated due to dangerous temperatures being reached.

The boiler has failed to ignite. Low gas pressure or a faulty ignition electrode are common causes.

Internal electronics fault on the main PCB.

Water pressure has dropped below the minimum operating level (0.5 bar).

Flame is being detected when the burner should be off — indicating a gas valve fault.

The fan is not running at the correct speed for safe operation.