23 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is failing to light the flame needed to produce heat or hot water.
Your boiler has detected a flame signal even though it is supposed to be turned off, which is a safety lockout to prevent potential gas build-up.
Your boiler has detected that it is dangerously hot and has shut itself down to prevent damage.
Your boiler has detected a recurring issue with venting exhaust gases and has shut itself down as a safety precaution.
Your boiler is trying to start but failing to light the flame, which means it has now locked itself out for safety reasons.
Your boiler has detected that the exhaust gases are not venting safely and has shut down to prevent the release of harmful fumes into your home.
Your boiler has detected repeated fluctuations in water pressure or flow, causing it to lock itself out three times in an hour to prevent potential damage to the system.
Your boiler has detected that the gases it is producing are significantly hotter than they should be, and it has turned itself off to prevent overheating.
Your boiler has stopped working because it is unable to accurately measure the temperature of the water being sent to your radiators or taps.
Your boiler is struggling to detect the temperature of the water coming out of your hot taps, which means it may fail to provide consistent hot water.
Your boiler has detected an issue with the sensor that monitors exhaust gases, meaning it has safely shut down to prevent the risk of harmful fumes entering your home.
Your boiler has detected an issue with one of its internal temperature sensors, which means it has safely shut down to prevent overheating.
Your boiler has detected that the internal fan is not working correctly, which prevents it from safely venting gases, so it has shut down to protect your home.
Your boiler has detected that the water pressure in your heating system has dropped too low to operate safely.
Your boiler has detected that the water pressure in your heating system is too high, which can put unnecessary strain on the internal components.
Your boiler is not receiving enough electricity from your home's power supply to run safely and consistently.
Your boiler is struggling to detect a consistent electricity supply, which is preventing it from starting up safely.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has lost the signal from the outdoor temperature sensor, meaning it cannot automatically adjust its settings based on the weather outside.
Your boiler has detected that the water pressure inside your heating system is too high, which prevents it from operating safely.
Your boiler has lost the ability to accurately measure the temperature of the water used for your radiators, causing it to shut down for safety reasons.
Your boiler's internal sensor is unable to detect how much water is in your heating system, so it has shut down as a precaution to prevent damage.
Your boiler has started an automatic process to remove trapped air from the system which usually happens after it has been turned on or serviced.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes