59 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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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 temporarily lost the signal from the sensor that monitors your hot water temperature.
Your boiler has lost connection to the temperature sensor inside its built-in hot water storage tank, meaning it cannot properly monitor or heat your stored hot water.
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 lost the ability to accurately measure your hot water temperature because of an electrical short in the temperature sensor.
Your boiler has detected an electrical fault with the sensor that measures the temperature of the internal hot water storage cylinder.
Your boiler has detected that it is getting too hot and has automatically shut down to prevent damage or overheating.
Your boiler has temporarily stopped working because the internal water pressure has dropped too low.
Your boiler has shut down because the water inside is getting too hot too quickly, usually caused by a blockage or trapped air preventing proper flow.
Your boiler is shutting down because the water inside is heating up much faster than normal, which usually points to a blockage preventing proper water flow.
Your boiler has automatically shut down because the exhaust gases leaving the system are dangerously hot.
Your boiler has detected an issue with the gas valve that controls the fuel supply, meaning it cannot safely ignite.
Your boiler has detected a signal that suggests a flame is present even when the burner is turned off, causing it to shut down for your safety.
Your boiler is trying to start up and ignite the gas, but the flame is failing to light.
Your boiler tried to light its flame several times but couldn't stay lit, so it has locked itself out for safety.
Your boiler has stopped working because it cannot detect that the internal fan, which safely pushes harmful gases outside, is spinning correctly.
Your boiler has lost the digital signal from a key internal component, meaning it cannot safely recognise its own setup and has stopped working to protect itself.
Your boiler is having trouble communicating with its external controllers or thermostats, preventing it from receiving instructions to heat your home.
Your boiler has temporarily stopped working because it cannot properly detect the flow of water and air through the system.
Your boiler has detected an unexpected flow of gas through the internal valve, meaning it has safely shut down to prevent any risk.
Your boiler is having trouble starting up because it is not receiving enough gas to ignite properly.
Your boiler has detected an issue with its internal carbon monoxide monitoring sensor, so it has safely shut down to protect you.
Your boiler has automatically shut down because it detected a dangerous level of combustion gases, which requires immediate attention from a qualified professional to ensure your safety.
Your boiler has temporarily stopped because it is running a specific sensor or calibration measuring test, which usually resolves itself or requires an engineer to complete the setup.
Your boiler has detected an issue with the internal gas valve control, meaning it cannot safely release gas to light the burner.
Your boiler has detected an issue with the gas valve shutting down properly, meaning it is safely locking itself out to prevent any potential safety hazards.
Your boiler's internal computer has encountered a memory error and cannot read the essential configuration data required to operate safely.
Your boiler has detected an internal electronic or sensor glitch and has safely shut down to prevent damage.
Your boiler has detected that the temperature of its internal electronic components is too high, so it has safely shut down to prevent permanent damage.
Your boiler has detected an internal communication problem with its electronic control system, meaning it cannot safely confirm the flame is burning correctly.
Your boiler has lost the ability to reliably detect the burner flame, so it has safely shut down to prevent unburnt gas from building up.
Your boiler has lost its electronic identity because a replacement part's memory chip wasn't programmed correctly during a recent repair or the main control board has suffered a memory error.
Your boiler is temporarily shutting down because a temperature sensor inside is reporting confusing or contradictory readings.
Your boiler has detected an unusual temperature difference between the water leaving it and the water returning, which usually points to a faulty temperature sensor.
Your boiler has detected that the water pressure inside the heating system is too low, so it has safely locked out to prevent damage.
Your boiler has detected that the internal water pressure is currently set much too high.
Your boiler has temporarily stopped because it cannot detect enough water pressure when the internal pump tries to start.
Your boiler has detected an issue with either the flap that controls exhaust gases or the pump that removes wastewater, leading to a potential blockage or overflow.
Your boiler has lost communication with an accessory sensor used for controlling your hot water.
Your boiler has detected an issue with the sensor that measures the incoming water temperature for its built-in hot water storage tank.
Your boiler is struggling to heat up your built-in hot water tank within the expected time, which usually affects your hot water supply.
Your boiler has detected an issue with the special electrical anti-corrosion system inside the hot water cylinder, meaning it needs a professional inspection to prevent internal wear.
Your boiler has detected that the water inside the system is not circulating properly because the temperature sensors are not registering the correct difference between the flow and return pipes.
Your boiler has detected an unusual mismatch between its internal temperature sensors, so it has safely stopped working to prevent damage.
Your boiler has temporarily stopped working because its temperature sensors are detecting confusing readings and need to be checked by a professional.
Your boiler has lost its connection to the built-in hot water storage tank, meaning it cannot properly manage your hot water supply.
Your boiler's built-in hot water storage tank has a faulty temperature sensor, meaning it cannot accurately monitor or regulate your hot water.
Your boiler has detected an issue with the gas valve feedback or calibration, meaning it has safely shut down to prevent incorrect combustion.
Your boiler has detected an internal configuration error, meaning the main control board and gas valve settings do not match correctly.
Your boiler has detected that the water flow and pressure sensors are sending confusing signals, which causes the system to stop operating for safety reasons.
Your boiler is currently running an automatic program to clear air bubbles out of the internal pipework and does not require a repair.
Your boiler is currently running a routine check of the water flow inside the system to ensure it is operating safely and effectively.
Your boiler has temporarily entered a routine testing mode used by engineers to check its efficiency.
Your boiler is currently running an internal self-test and is temporarily paused because it is checking the sensor that monitors water coming back into the system.
Your boiler is currently running a routine internal check on its water pressure sensor to ensure it is working correctly.
Your boiler is performing a routine internal check on its temperature sensors, which is normally a temporary diagnostic message.
Your boiler is simply running a routine internal check on its main computer and safety systems, which is completely normal.
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BoilerFaultCodes