87 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 a false flame signal when the burner is not actually supposed to be lit, so it has safely locked out to prevent any risk.
Your boiler was running, but the flame went out unexpectedly, causing it to stop heating.
Your boiler has temporarily stopped working because an external safety switch, such as a smart thermostat or underfloor heating control, has locked the system.
Your boiler's internal computer is having trouble recognising a core internal part, so it has safely shut down to prevent any issues.
Your boiler has detected an electrical problem with the component that controls the gas supply, meaning it has safely shut down to prevent unsafe operation.
Your boiler is confused because its internal computer board and its identification settings do not match up correctly.
Your boiler has detected an internal system communication error and has safely shut down to prevent further issues.
Your boiler has detected an internal electronic failure within its main control system and has safely stopped working.
Your boiler's main control unit is experiencing a communication error or electrical glitch that is preventing it from operating correctly.
Your boiler's main control computer is experiencing a temporary glitch or internal error, which has caused it to stop working for safety reasons.
Your boiler's internal computer is experiencing a communication error, meaning it has safely shut itself down to prevent potential damage.
Your boiler's internal computer is experiencing a communication error and cannot safely manage the heating or hot water systems.
Your boiler's internal computer is experiencing a communication error or technical failure, preventing it from operating correctly.
Your boiler's internal computer is experiencing a communication error, meaning it has safely shut down to prevent incorrect operation.
Your boiler's internal computer is experiencing a temporary communication error, causing it to stop operating as a protective measure.
Your boiler's internal computer has encountered a critical communication error, meaning it has safely shut itself down to prevent potential damage.
Your boiler’s internal computer is experiencing a software glitch or a communication error that is preventing it from running safely.
Your boiler's internal computer is experiencing a communication error, meaning it has safely shut down to prevent incorrect operation.
Your boiler's computer has encountered an internal error and cannot operate, which means you currently have no heating or hot water.
Your boiler has detected an internal electrical problem with its main computing brain, preventing it from operating safely.
Your boiler has detected an internal electronic or control system error that is stopping it from operating safely.
Your boiler has detected an internal communication error and has safely shut down to prevent potential damage to its electronic components.
Your boiler's internal computer is experiencing a software or communication error and needs to be restarted or investigated by a professional.
Your boiler has detected an internal electronic error with its main control board, which has temporarily shut it down for safety.
Your boiler is temporarily pausing because it is producing more heat than your home is currently asking for.
Your boiler has run a routine internal safety check on its main electrical switches, but it needs an engineer to clear the code and check the internal control board.
Your boiler has temporarily stopped working because it cannot reliably detect or keep the burner flame lit.
Your boiler has temporarily stopped working because the flame and internal airflow were unexpectedly interrupted.
Your boiler has detected that water is not circulating properly through the system because the internal pump is either jammed or trapped air is blocking the flow.
Your boiler is simply preparing to ignite and fire up its burner as part of its normal heating cycle.
Your boiler has detected an issue with the internal valve that controls the precise mix of air and gas needed for safe, efficient burning.
Your boiler has detected that a flame is still present briefly after the gas supply has been shut off.
Your boiler is running a temporary ventilation check to clear any stale air from the system before it attempts to fire up safely.
Your boiler is automatically running a routine cycle to prevent the internal pump from getting stuck, which is a normal maintenance feature.
Your boiler has detected an internal electronic communication error, meaning it has temporarily stopped working for safety.
Your boiler's main electronic control system has experienced an internal communication failure and cannot identify its own components.
Your boiler has detected an internal electronic or control board error and has safely shut down to prevent damage.
Your boiler has detected an internal communication error and has safely shut itself down to prevent it from operating incorrectly.
Your boiler is receiving incorrect temperature readings because a sensor attached to a specialist heating component is failing, which may temporarily stop your heating system from working properly.
Your boiler's main control board has lost its connection to the user display or thermostat, meaning it cannot receive instructions to heat your home.
Your boiler has detected that the burner is running at its maximum capacity for too long, causing it to proactively shut down to prevent overheating.
Your boiler is simply reminding you that it is due for its annual safety service.
Your boiler has identified that the internal water pump is not the correct type for this specific model, which is preventing the system from operating correctly.
Your boiler has lost the connection to the temperature sensor in your hot water tank, meaning it cannot tell how hot the water is.
Your boiler has been running for a very long period without a break and has automatically paused to prevent overheating.
Your boiler is struggling to accurately monitor the temperature of the water returning to it, so it has stopped working to prevent potential overheating.
Your boiler has lost connection with its outdoor temperature sensor, so it is running at a constant safe temperature to keep your home warm while it waits for a fix.
Your boiler is having trouble measuring either the outside temperature or the oxygen levels in the flue, which is preventing it from running efficiently or starting up correctly.
Your boiler is simply reminding you that its annual service is due soon to keep it running safely and efficiently.
Your boiler is simply reminding you that it is time for its annual health check and service to keep it running efficiently and safely.
Your boiler is simply reminding you that it is time for its regular annual service to ensure it continues to run safely and efficiently.
Your boiler has temporarily stopped working because a temperature monitoring sensor has detected an electrical wiring or internal fault.
Your boiler has temporarily stopped working because it has lost the electronic signal from one of its internal temperature sensors.
Your boiler's internal computer has encountered a critical electronic failure and can no longer communicate with its own sensors or controls.
Your boiler's internal computer has encountered a communication error or technical glitch that is preventing it from running properly.
Your boiler has detected an issue with how exhaust gases are being discharged, causing it to shut down for safety.
Your boiler's computer is having trouble communicating with its internal systems, which has caused it to shut down for safety reasons.
Your boiler's main internal computer has encountered a memory or communication error, preventing the system from running safely.
Your boiler has detected an internal electrical communication error, meaning it cannot properly coordinate its functions to provide heat and hot water.
Your boiler has detected an issue with the flame and has shut down as a safety precaution to ensure no unburnt gas is escaping.
Your boiler has detected an internal electrical system issue and has safely shut down to prevent damage.
Your boiler has detected an internal electrical problem that is preventing it from starting up safely.
Your boiler has experienced an internal electrical error that has caused it to stop working for safety.
Your boiler's internal computer has detected a general electrical communication error and has shut down as a safety precaution.
Your boiler's main control unit has detected an electrical communication failure, meaning the system cannot safely operate your heating or hot water.
Your boiler has detected an internal software or communication error that is preventing it from operating safely.
Your boiler's internal computer has encountered a communication error or hardware glitch and needs a professional inspection to determine if the main control board is failing.
Your boiler has detected an internal safety fault in its main electronic brain and has safely shut down.
Your boiler's computer brain has detected an internal electronic chip that doesn't match the model or has become loose.
Your boiler is struggling to stay lit when running at a low power level, which is preventing it from providing steady heating or hot water.
Your boiler is struggling to detect a flame when it tries to work at full power, meaning it cannot provide consistent heating or hot water.
Your boiler is trying to ignite but cannot detect a flame, meaning it is currently unable to provide heating or hot water for safety reasons.
Your boiler keeps trying to light, but the flame goes out repeatedly and it has safely locked itself out.
Your boiler has detected an internal error while trying to confirm it is burning fuel correctly, and it has shut down as a safety precaution.
Your boiler is confused by its current settings or software programming and needs a professional to reconfigure it.
Your boiler's internal settings or water system configuration have not been properly recognized, which stops it from operating correctly.
Your boiler's internal electronic control system has identified a technical failure that requires an expert to reset or replace the faulty circuit board.
Your boiler has stopped working because it cannot confirm that the internal fan, which is essential for safely exhausting gases, is running correctly.
Your boiler has stopped working because it cannot move the air and exhaust gases through the system properly.
Your boiler has stopped working because it is unable to accurately read the temperature of the water inside the unit.
Your boiler has shut down because the water circulating inside it is getting much hotter than it should perfectly safely be.
Your boiler is heating up too quickly because the water inside cannot flow away fast enough to cool the system down.
Your boiler has detected that the internal water pressure has dropped too low and needs to be topped up.
Your boiler's automatic filling system has topped up the water pressure too many times in a short period, suggesting there may be a leak in your heating system.
Your boiler is struggling to work because the electricity supply coming from your home's wall socket or wiring is weaker than it needs to be.
Your boiler has locked itself for safety due to a temporary operating error and needs to be reset.
Your boiler has safely locked itself out and stopped working due to an internal safety trigger, but you may be able to restart it by using the control panel buttons.
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.
BoilerFaultCodes