29 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 start because it cannot light the internal flame needed to provide your heating and hot water.
Your boiler has detected a flame signal when it is not supposed to be running, which forces a safety shutdown to prevent any risk.
Your boiler has detected that it is running too hot and has automatically switched itself off to prevent any damage or safety issues.
Your boiler has stopped working because it cannot confirm that the internal fan, which clears exhaust gases, is spinning correctly.
Your boiler has detected that the exhaust gases are becoming dangerously hot, so it has safely shut itself down to prevent internal heat damage.
Your boiler is failing to detect the flame correctly, so it has safely shut down to prevent any gas buildup.
Your boiler has detected an issue with the internal mechanism that controls the gas supply, meaning it cannot safely start up to provide heat or hot water.
Your boiler's main computer is having trouble communicating, which has caused the system to stop working entirely.
Your boiler's internal computer is struggling to confirm the temperature difference between the water leaving and returning to the unit, causing it to shut down for safety.
Your boiler's internal computer is experiencing a communication error, which has caused it to shut down for safety reasons.
Your boiler is struggling to detect the correct amount of water inside the system, which is preventing it from firing up.
Your boiler has detected that you have added water into the system too many times today, which suggests there is a leak somewhere in your radiators or pipework.
Your boiler's central computer is struggling to communicate properly, causing the system to shut down for safety reasons.
Your boiler is trying to start but the flame is cutting out immediately, which means it cannot safely heat your water or home.
Your boiler has lost the ability to detect water flowing through the system, so it has shut down to prevent potential damage.
Your boiler has lost the signal from the sensor that monitors the flow of water, meaning it cannot confirm if the system is safe to fire up.
Your boiler is struggling to accurately measure the temperature of your hot water because a sensor is sending an incorrect signal, meaning you likely have no hot water available.
Your boiler has lost the connection to the sensor that monitors your hot water temperature, meaning it cannot reliably heat your taps.
Your boiler is detecting that it isn't receiving enough electricity from your home to operate correctly.
Your boiler is struggling to detect a steady flow of electricity, which is likely caused by a minor power dip or a faulty electrical connection in your home.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler's electronic control panel is experiencing an internal error and is unable to restart, effectively locking the system for safety.
Your boiler has detected that there is too much water inside your heating system, which is causing excess pressure.
Your boiler's main internal computers have lost their connection, meaning the controls on the front panel can no longer talk to the heating unit.
Your boiler is struggling to read the temperature of the water returning to it because a sensor or its wiring is miscommunicating.
Your boiler has lost its connection to the sensor that monitors the temperature of water returning to the unit, causing it to stop operating as a safety precaution.
Your boiler has detected an issue with the sensor that monitors the temperature of the gases leaving your flue, causing it to shut down for safety.
Your boiler has lost its connection to a safety sensor that monitors the temperature of the gases leaving your flue, causing the system to stop working as a precaution.
Your boiler has detected a generic electronic communication failure, meaning the main control board is unable to send or receive signals reliably.
BoilerFaultCodes