24 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Main Eco Compact
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 a problem with a internal sensor that monitors water temperature, meaning it cannot safely heat your home or water.
Your boiler is failing to clear its system of air before starting, so it has safely shut down to prevent ignition.
Your boiler is failing to light the fuel inside even though it is trying to start, so it has safely shut itself down to prevent a gas build-up.
Your boiler's internal computer has crashed or is struggling to process the reset command, preventing it from starting up again safely.
Your boiler is lighting up but shutting off shortly after because it cannot confirm that the flame is staying on, meaning you currently have no heating or hot water.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler is failing to light properly or stay lit, meaning your heating and hot water will not work until it is reset or repaired.
Your boiler has reached an unsafe temperature or detected excessive heat in the exhaust, causing it to shut down for safety.
Your boiler has stopped working because water is not circulating correctly through the system to prevent it from overheating.
Your boiler has detected an issue with how it clears exhaust gases, which has caused the system to shut down for safety.
Your boiler is struggling to detect the temperature of the water coming from your taps, which means it cannot reliably provide hot water.
Your boiler is currently unable to read the temperature of the water being sent to your radiators, which has caused it to shut down for safety.
Your boiler is struggling to clear exhaust fumes or draw in fresh air, so it has safely shut down to prevent any risk.
Your boiler has detected that it is overheating and has automatically switched itself off to prevent damage.
Your boiler is struggling to clear exhaust gases safely, so it has stopped working to prevent any risk of fumes entering your home.
Your boiler is struggling because it cannot detect enough water circulating through the system or the pressure level has dropped too low.
Your boiler is struggling to detect the temperature of the water for your taps, which means it cannot reliably provide hot water.
Your boiler is currently unable to monitor the temperature of the water being sent to your radiators, so it has stopped working to prevent potential overheating.
Your boiler is having trouble measuring the temperature of your hot water, which likely means your taps and shower are running cold.
Your boiler's internal thermometer for the heating system has stopped working correctly, so it has shut down to prevent itself from overheating.
Your boiler thinks a hot water tap is turned on even when all taps are closed, which prevents the heating from working correctly.
Your boiler has stopped working because the internal fan, which safely exhausts fumes, isn't spinning correctly or communicating with the control board.
Your boiler has failed to ignite the gas burner, which means it cannot heat your water or radiators.
Your boiler has attempted to light the gas burner multiple times but has failed to detect a flame, causing it to shut down for safety reasons.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes