Select a fault code

The return temperature sensor is reading outside normal range or has failed.

The fan is not reaching the required speed for safe operation.

Fan speed is outside the safe operating range.

A fault with the gas valve has been detected. The valve controls gas flow to the burner.

A fault with the gas valve relay on the PCB.

The domestic hot water temperature sensor has developed a fault.

A fault with the fan or flue has been detected. The boiler cannot safely vent combustion gases.

The flow temperature sensor is reading outside normal parameters or has failed. The boiler cannot safely monitor outgoing water temperature.

The boiler has shut down due to excessive temperature. Causes include a blocked heat exchanger, poor pump circulation, or low water flow.

The safety thermostat has activated, cutting out the boiler due to dangerously high temperatures.

The boiler failed to ignite during a start-up attempt. Low gas pressure, a faulty igniter, or a dirty electrode are common causes.

An internal fault on the PCB has been detected. This typically requires component-level diagnosis.

System pressure has fallen below the minimum operating level. This is one of the most common boiler issues.

The flame sensor is detecting a flame when the burner should not be lit. This is a serious fault indicating a gas valve issue.

The fan is not operating correctly. Without a functioning fan, combustion gases cannot be safely expelled.

The burner has failed to light after the maximum number of ignition attempts.