16 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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 is detecting a flame inside the unit even when it has been told to turn off, which means it cannot safely restart.
Your boiler has detected an electrical fault in its internal control wiring and has safely shut itself down to prevent further damage.
Your boiler is failing to light the burner despite several attempts, meaning it cannot produce heat or hot water.
Your boiler experienced a temporary loss of power while it was trying to shut itself down safely, which has caused it to pause operation.
Your boiler has detected an issue caused by an external factor, such as a problem with your electrical power supply, an external sensor, or a communication fault from your heating controls.
Your boiler's internal computer is having trouble talking to its main control board, which means it cannot operate safely and has shut down.
Your boiler has detected that the water inside the system is getting hotter than it safely should and has shut itself down to prevent damage.
Your boiler has detected that the water returning to it from your radiators is much hotter than expected, causing it to shut down to prevent overheating.
Your boiler has detected that hot water is flowing back into the system in the wrong direction or at a higher temperature than the supply water, which usually points to a sensor or circulation fault.
Your boiler has stopped working because a sensor that measures the water temperature is malfunctioning and sending an incorrect signal.
Your boiler's temperature gauge has developed an electrical fault, causing it to misread the water temperature and shut the system down as a precaution.
Your boiler has lost the ability to measure how hot the water is inside the system, so it has safely shut itself off to prevent overheating.
Your boiler has lost the ability to accurately measure the temperature of the water circulating back into it, so it has turned itself off as a safety precaution.
Your boiler's computer has detected that its configuration settings are not configured correctly, preventing it from operating safely.
Your boiler’s internal computer has encountered a critical error and can no longer safely operate, meaning your heating and hot water have stopped.
Your boiler is failing to detect the flame needed to heat your home, and it has exhausted all automatic attempts to restart itself.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes