23 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Micron System
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
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Your boiler has detected an internal electrical error or a component failure during its startup sequence that is preventing it from firing up.
Your boiler’s internal control board has developed a critical electronic fault and can no longer manage the heating process safely.
Your boiler has entered a safety lockout mode because it failed to light or stay on properly after multiple attempts.
Your boiler has detected an internal electrical or computer error and has stopped working for safety.
Your boiler has failed to ignite and has locked itself out for safety, meaning you currently have no heating or hot water.
Your boiler is working exactly as it should and is currently heating the water for your radiators or taps.
Your boiler is operating normally and is currently heating the water for your radiators or hot water tank.
Your boiler's burner stays lit even when it should turn off, meaning it isn't responding to your thermostat or timer settings.
Your boiler has switched itself off because it has reached an unsafe temperature and needs to be cooled down and reset.
Your boiler has failed to light after several attempts and has locked itself out for safety.
Your boiler is operating normally and the central burner is currently ignited and heating your water.
Your boiler is receiving electrical power and is in standby mode or waiting for a signal to heat up.
Your boiler is receiving a request to turn on the heating or hot water, but it has not yet successfully fired the burner.
Your boiler has stopped working because it thinks the fan is spinning but it isn't receiving the correct signal to proceed with lighting the burner.
Your boiler is operating normally and the burner has successfully ignited to provide heating or hot water.
Your boiler has shut down because it has detected it is getting too hot, usually caused by a blockage or a pump failure.
Your boiler is failing to light or stay lit, meaning it cannot heat your home or water.
Your boiler has sensed it is getting too hot and has shut itself down as a safety precaution.
Your boiler has switched itself off because it got too hot, likely triggered by a safety sensor to prevent damage.
Your boiler has become too hot and has automatically shut down to protect itself, usually because the water inside isn't circulating properly.
Your boiler has switched itself off because it has reached an unsafe temperature, usually caused by a circulation issue or a temporary blockage.
Your boiler has become confused while trying to start up and has stopped working for safety reasons.
Your boiler's internal computer brain has encountered a glitch or failure and is struggling to run its operating system.
BoilerFaultCodes