21 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is trying to start up but cannot successfully light the internal flame to provide heat or hot water.
Your boiler has detected heat or a flame inside the unit when it should be turned off, which is a significant safety precaution.
Your boiler has detected that it is running too hot and has automatically turned itself off to prevent damage.
Your boiler has detected multiple issues with its internal temperature sensing or airflow, causing it to lock itself down for safety.
Your boiler has stopped working because it cannot detect if the fan, which is essential for safely venting exhaust gases, is spinning correctly.
Your boiler has tried to light the burner several times but failed, so it has safely shut itself down to prevent a build-up of unburnt gas.
Your boiler's water pressure sensor is providing an incorrect reading, which is preventing the system from heating your water correctly.
Your boiler is struggling to clear exhaust fumes properly, which means it has safely shut down to prevent the build-up of dangerous gases.
Your boiler is struggling to detect if water is moving through the pipes, which prevents it from heating your home or water safely.
Your boiler has lost the ability to accurately measure the temperature of the water coming back into the system, so it has safely shut down to prevent overheating.
Your boiler is struggling to detect the temperature of the water used for your taps and shower, meaning it cannot reliably heat your hot water.
Your boiler has detected a problem with the sensor that monitors the temperature of the gases leaving your flue, causing it to shut down for safety reasons.
Your boiler is not detecting the flow of water, which prevents it from starting up correctly to provide heating or hot water.
Your boiler has stopped working because the fan system that clears out exhaust gases is not operating correctly, preventing the boiler from lighting safely.
Your boiler has detected that the incoming electricity supply is too weak to operate the system safely.
Your boiler is struggling because the electricity supply coming into your home is not steady or is fluctuating outside of the normal range.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Your boiler has lost its connection to the outside temperature thermometer, so it can't automatically adjust your heating based on the weather.
Your boiler is struggling to detect the flow of water because a sensor inside the unit is providing an incorrect reading, which prevents it from safely heating your home or water.
Your boiler has stopped working because the amount of water inside your heating system has dropped too low to operate safely.
Your boiler is currently failing to light the flame it needs to produce heat and hot water.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes