19 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler has detected that the water temperature is too high and has shut down to prevent damage to its internal components.
Your boiler has stopped working because it failed to light the flame after several attempts, usually due to a lack of gas supply or an ignition problem.
Your boiler has detected a flame when there shouldn't be one, or the sensor incorrectly thinks a fire is lit, causing it to shut down for safety.
Your boiler has shut down because it has reached an unsafe temperature, triggered by a safety sensor that prevents the unit from overheating.
Your boiler has stopped working because the fan that removes waste gases is not spinning or communicating correctly with the system.
Your boiler has detected that the water pressure is either too low or the sensor that monitors it is not communicating correctly.
Your boiler has detected that the water pressure is incorrect or the sensor that monitors it is not communicating properly.
Your boiler has lost the ability to measure the water pressure accurately, which has caused it to stop running for safety.
Your boiler has detected an issue with its incoming electrical power supply, which is often caused by a voltage surge or a fault on the main circuit board.
Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold.
Your boiler has detected an electrical issue with the part that controls how much gas is burned, causing the system to shut down for safety.
Your boiler has detected an issue with the sensor that monitors the water temperature in your main heating circuit, which may prevent your radiators from warming up correctly.
Your boiler has detected that the water returning from your radiators is too hot or the temperature difference is incorrect, causing the system to shut down for safety.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
Your boiler has detected a blockage in the flue pipe that is preventing waste gases from safely exiting your home.
Your boiler has sensed that the exhaust fumes are getting too hot and has shut down as a safety precaution to prevent damage.
Your boiler has detected that the main part responsible for heating your water is becoming blocked or dirty and needs a professional service.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
BoilerFaultCodes