41 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 is failing to light because it cannot detect a flame, meaning you currently have no heating or hot water.
Your boiler has detected that it is dangerously hot and has shut itself down to prevent damage, likely because water is not flowing properly through the system.
Your boiler has detected an issue with its exhaust system, meaning it cannot safely clear waste gases and has shut down to prevent a hazard.
Your boiler is trying to start but keeps failing to light the internal flame needed to heat your water.
Your boiler is failing to ignite because it cannot detect a flame, meaning you currently have no heating or hot water.
Your boiler has failed to light the flame needed to produce heat or hot water.
Your boiler is detecting a flame inside its internal chamber when the burner should be completely switched off, which is a safety concern regarding the burner's operation.
Your boiler has detected that it is dangerously overheating and has automatically shut itself down to prevent damage.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.
Your boiler has detected that the internal fan responsible for safely exhausting fumes is not spinning at the correct speed, so it has stopped working to prevent a safety issue.
Your boiler has detected that the gases leaving through your flue are too hot, suggesting the internal cooling system or heat exchanger is struggling to transfer heat correctly.
Your boiler's internal temperature sensor is failing to detect the water temperature returning to the unit, causing the system to stop working to protect itself.
Your boiler is struggling to detect the temperature outside, so it is defaulting to a standard operation mode to ensure you still have heating and hot water.
Your boiler has stopped working because it cannot correctly read the temperature of the water flowing through your heating system.
Your boiler is not currently able to heat your home because it cannot detect the temperature of the water returning to it.
Your boiler is struggling to detect the temperature of your hot water supply, which means it has stopped heating your water to prevent it from getting too hot.
Your boiler has detected a problem with the sensor that monitors the temperature of the gases leaving your home, causing the system to stop working as a safety precaution.
Your boiler has stopped heating your home or water because a sensor that measures the temperature of the circulating water is sending an incorrect or missing signal.
Your boiler's internal extraction fan is failing to start or spin fast enough to clear waste gases, so the system has locked out to keep you safe.
Your boiler has stopped working because it is unable to accurately measure the temperature of the water inside the unit.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.
Your boiler's air intake or exhaust monitoring system has lost its connection, preventing the unit from starting safely.
Your boiler has identified a missing safety link on its internal computer board, which prevents it from starting up correctly.
Your boiler is struggling because the electricity supply feeding it is unstable or 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 is struggling to read the outside temperature because the sensor mounted on your external wall is either damaged or has lost its connection.
Your boiler is signalling that the water pressure inside your heating system has risen too high, preventing it from operating safely.
Your boiler has lost the internal connection needed to fire up the burner, so it cannot provide any heating or hot water until the communication link is restored.
Your boiler has detected a disagreement between two of its temperature sensors and has shut down as a precaution to prevent overheating.
Your boiler has detected that the water inside isn't moving properly and is about to overheat, so it has shut down to prevent damage.
Your boiler is unable to measure the water pressure inside the system because the sensor that monitors it has failed or is disconnected.
Your boiler is struggling to control the gas supply to the burner, meaning it cannot produce heat or hot water safely.
Your boiler has stopped working because the mechanical component responsible for circulating air and exhausting combustion gases is not receiving power or has failed.
Your boiler has stopped working because it can no longer accurately read the temperature of the exhaust chimney, meaning it has shut down as a safety precaution.
Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.
The computer that controls your boiler is experiencing an internal error, which means the system cannot safely start or regulate your heating and hot water.
Your boiler is failing to light the flame needed to produce heat and hot water.
Your boiler has lost the ability to measure the temperature of the water leaving it, which means it has safely shut down to prevent overheating.
Your boiler has lost the ability to measure the temperature of the water returning to it, so it has safely shut down to prevent overheating.
Your boiler has detected that it is dangerously overheating because the water is failing to flow through the system as it should.
Your boiler has shut itself down because it isn't moving water around properly, causing it to dangerously overheat.
BoilerFaultCodes