Select a fault code

The burner has failed to ignite after the maximum number of attempts. Common causes include low gas pressure, a faulty ignition electrode, or a blocked condensate pipe.

The flow temperature has exceeded the safe limit. This may indicate a circulation problem or a faulty thermostat.

The flame went out unexpectedly during operation. This can be caused by a brief gas supply interruption, a draught, or a gas pressure fluctuation.

The thermal cut-off device has tripped. This is a safety device that operates if the boiler overheats significantly.

The boiler's overheat thermostat has activated, meaning the boiler has reached an unsafe temperature. Causes include a blocked heat exchanger or poor circulation.

The fan is not operating correctly or the flue system has a problem. Safe combustion is not possible.

The flow temperature sensor (NTC thermistor) has failed or is reading an incorrect temperature.

The return temperature sensor has failed or is reading an incorrect temperature.

A fault has been detected on the boiler's main PCB.

The boiler's flame detection circuit is sensing a flame when the burner should not be lit. This is a serious fault indicating a gas valve or ionisation circuit fault.

The system water pressure has fallen below the minimum operating level. This is one of the most common boiler faults and is usually simple to fix.

The pump is running after the boiler has shut down to protect the heat exchanger. This is a normal function but can indicate a fault if it occurs very frequently.

The overheat thermostat has locked out the boiler due to dangerously high temperatures.

The condensate probe or drain is blocked. Condensate cannot drain away from the boiler.