71 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's display screen has lost its connection to the main computer inside, meaning it cannot control or run your heating system.
Your boiler has lost its connection to the temperature sensor, meaning it no longer knows how hot the water is and has stopped working to keep you safe.
Your boiler has lost the connection to the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety reasons.
Your boiler has stopped working because a sensor that measures water temperature is providing an incorrect signal, so the system has safely shut down to prevent overheating.
Your boiler has detected a faulty signal from a heat sensor, causing it to shut down for safety to prevent overheating.
Your boiler has temporarily stopped working because it has detected a faulty reading from its internal temperature sensor.
Your boiler has automatically shut down because the internal water pressure has dropped too low to operate safely.
Your boiler has shut itself down because the water inside is getting too hot too quickly, usually due to a blockage or a stuck valve.
Your boiler is temporarily shutting down because the water inside is heating up much faster than normal, usually due to poor water flow.
Your boiler has automatically shut down because the exhaust gases are getting too hot, or a safety connection linked to the flue has come loose.
Your boiler has temporarily locked out because it falsely detects a flame inside when it shouldn't be there, usually due to moisture on the internal electronics or a faulty valve.
Your boiler is trying to start up, but it cannot detect a successful flame to get the heating or hot water going.
Your boiler tried to fire up several times but couldn't keep the flame going, so it has safely shut itself down.
Your boiler has stopped working because it cannot detect that its internal fan is spinning properly to safely clear exhaust gases.
Your boiler has detected an electrical communication problem in its internal wiring control system, causing it to shut down to protect its internal electronics.
Your boiler has detected an electrical fault with the gas valve, meaning it cannot safely open to let gas through for heating and hot water.
Your boiler has detected an issue with the gas valve not shutting off properly, which means a qualified engineer must inspect it immediately for safety.
Your boiler's main computer control panel has suffered a critical internal memory failure and can no longer process instructions to run your heating system.
Your boiler has detected a sudden reading error with its internal temperature sensors or main control board, causing it to lock out for safety.
Your boiler has detected that its internal computer is running too hot and has safely shut down to prevent permanent damage.
Your boiler has temporarily stopped working because the internal computer is receiving a confusing signal from the flame sensor.
Your boiler is safely shutting down because the burner flame is flickering or going out unexpectedly, which can be caused by gas supply issues or a blocked exhaust.
Your boiler's main computer is experiencing an identity crisis because a replacement part was recently installed without being programmed correctly to match your specific model.
Your boiler has temporarily stopped working because a sensor measuring the water temperature is giving a constant or incorrect reading.
Your boiler has temporarily stopped working because it has detected a disagreement between its temperature sensors, meaning it cannot safely measure how hot the water is.
Your boiler is not receiving a proper signal from its water pressure sensor, meaning it cannot accurately check the water level inside the system.
Your boiler has detected an electrical fault with the internal water pressure sensor, which is reading a pressure signal that is too high.
Your boiler has detected that the water pressure isn't rising correctly when the internal pump starts up, which usually points to low system pressure, trapped air, or a faulty sensor.
Your boiler has automatically shut down because a safety device detected that the main part of the boiler has become dangerously hot.
Your boiler has detected an issue with the system that removes waste water or controls the exhaust gases, causing it to lock out for safety.
Your boiler has detected that the water inside is not heating up or moving properly right after it turns on.
Your boiler has detected that the temperature sensors measuring how water enters and leaves the system are giving contradictory or reversed readings.
Your boiler's temperature sensors have been attached to the wrong pipes during installation, meaning it cannot properly measure how water flows through the system.
Your boiler has lost its electrical connection to the part that creates the ignition spark, meaning it cannot safely light to provide heating or hot water.
Your boiler has lost its electrical connection to the gas valve, meaning it cannot safely let gas through to heat your home.
Your boiler has detected an issue with the internal water pump's connection or electronic signals, causing it to shut down for safety.
Your boiler's internal computer has failed a self-test and is no longer able to communicate with the rest of the system.
Your boiler is currently in standby mode because it has not been asked to provide any heating or hot water at this moment.
Your boiler is simply getting ready to start up for your heating by running its internal fan, which is a normal part of the ignition process.
Your boiler is simply getting ready to start the heating by running the internal water pump for a few moments, which is a normal part of its startup routine.
Your boiler is currently in the middle of its normal startup process to begin heating your radiators.
Your boiler is operating normally and is currently heating your radiators.
Your boiler is currently cooling itself down by circulating water and venting air, which is a normal part of the shutdown process after your heating has been running.
Your boiler is simply performing a routine safety cycle to clear any leftover heat after the burners have turned off.
Your boiler is simply finishing its cooling process after the heating has turned off, and this is a normal part of its operation.
Your boiler is simply taking a short, scheduled rest period after completing a heating cycle to allow the water temperature to balance.
Your boiler has simply registered a normal request to heat up your hot water cylinder.
Your boiler is simply getting ready to supply hot water by checking the ventilation fan before it fires up.
Your boiler is simply preparing to heat your hot water by running the internal pump before turning on the burner.
Your boiler is simply preparing to heat your hot water and is about to ignite the burner, which is a normal part of its daily operation.
Your boiler is currently operating normally and is in the process of heating your radiators.
Your boiler is currently just finishing a routine cooling-down process after providing hot water and should return to normal operation shortly.
Your boiler's fan is attempting to spin, but the electronic control board isn't receiving the correct signal back to confirm it is working properly.
Your boiler is simply finishing its cooling cycle after providing hot water and is operating exactly as it should.
Your boiler has temporarily paused heating your hot water to let things cool down or adjust, which is a normal safety feature rather than a breakdown.
Your boiler is working perfectly, but it is currently being told to stay off by your room thermostat or smart home control system.
Your boiler is currently in summer mode or waiting for a heating signal from your thermostat, which is a normal standby state rather than a fault.
Your boiler is pausing because its internal air-flow system is not operating at the correct speed to run safely.
Your boiler is temporarily running its pump to prevent the internal pipes from freezing, which is a normal protective feature during very cold weather.
Your boiler has detected that an external safety switch for your underfloor heating system is currently open, preventing the heating from turning on.
Your boiler has detected that a safety flap in the exhaust pipe is stuck in the closed position, which prevents the unit from venting fumes safely and stops it from starting up.
Your boiler has automatically triggered its internal heater to keep its components from freezing in cold weather.
Your boiler has temporarily paused because it has detected a lack of water or poor flow through the system.
Your boiler has temporarily paused because the water pressure is too low or the water isn't circulating properly between the pipes.
Your boiler is currently running an automatic air-clearing cycle to remove trapped air from the system, which is a normal process after recent maintenance or a pressure drop.
Your boiler is currently set to a special demonstration mode used for showroom displays, which prevents it from heating your home or water normally.
Your boiler is currently performing a self-check of its internal sensors and has temporarily paused heating and hot water to ensure everything is operating safely.
Your boiler is currently running a self-check process, which is temporarily pausing your heating and hot water to ensure everything is working correctly.
Your boiler is currently running an internal software check and should return to normal operation automatically once the process completes.
Your boiler is currently running a quick safety check of its internal air ventilation before it starts the heating process.
Your boiler is currently in a temporary standby state and is not actively heating, often because the system has been switched off at the controls or is waiting for a signal from your thermostat.
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BoilerFaultCodes