67 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is failing to ignite the flame needed to heat your water and home.
Your boiler is failing to light the flame or is unable to detect that it has successfully turned on, so it has shut itself down as a precaution.
Your boiler is struggling to clear exhaust gases because the internal fan responsible for ventilation is not responding correctly.
Your boiler is failing to ignite because it cannot open the internal valve that regulates the flow of gas.
Your boiler is struggling to read its own temperature because one of its internal sensors is disconnected or has stopped working correctly.
Your boiler has detected that the internal component responsible for transferring heat to your water and radiators is failing or clogged.
Your boiler's internal pressure management system is failing, which means it cannot safely handle the expansion of water as it heats up.
Your boiler has detected an internal communication error between its electronic brains, meaning it has safely shut down to prevent incorrect operation.
Your boiler has detected an internal electrical fault with its main power component, meaning it cannot operate safely and has shut down.
Your boiler is unable to move water around the system because the pump has either seized or stopped working.
Your boiler is struggling to clear exhaust gases safely, so it has shut down to prevent any risk of fumes entering your home.
Your boiler is struggling to push water around your heating system, usually because too many radiators are turned off or there is a blockage in the pipes.
Your boiler is struggling to direct hot water to your taps or radiators because a motorized internal valve is stuck or failing to signal correctly.
Your boiler is struggling to accurately read or maintain the necessary water pressure required to keep your heating and hot water running safely.
Your boiler is failing to detect the flow of water, which will likely prevent it from starting up or producing hot water.
Your boiler is struggling to exchange heat effectively to provide hot water, which may cause your hot tap water to run cold or the system to stop working entirely.
Your boiler has detected that the internal safety system intended to release excess pressure has been triggered, which can lead to leaks and equipment damage.
Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit due to a sensor or wiring fault.
Your boiler has stopped working because one of its internal temperature sensors is unable to send a signal to the main control board.
Your boiler has detected an electrical fault with the internal temperature sensor that monitors the outward flow of water, causing the system to shut down for safety.
Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has detected a short circuit.
Your boiler has switched itself off because it has become too hot internally, usually due to a lack of water flow or a blockage.
Your boiler has detected that there is not enough water pressure or flow to operate safely and has shut down to prevent overheating.
Your boiler has detected that the water isn't moving through the system correctly, causing it to heat up too quickly and shut down for safety.
Your boiler is heating up too quickly because water isn't moving through the system properly, causing it to shut down to prevent overheating.
Your boiler has detected a flame when there shouldn't be one, which has caused it to shut down for safety.
Your boiler is failing to light because it isn't receiving gas or the ignition system isn't creating a spark.
Your boiler has lost its flame while running and cannot restart, likely because it is not getting enough gas or the ignition system is failing.
Your boiler has stopped working because the internal fan isn't spinning at the correct speed to safely clear away exhaust fumes.
Your boiler has stopped working because it cannot confirm that harmful exhaust fumes are being safely cleared away through the flue pipe.
Your boiler has stopped working because the fan that clears exhaust gases is not spinning at the correct speed or the sensor that monitors it has failed.
Your boiler has lost its memory regarding the type of gas it uses and needs to be reconfigured by a professional to operate safely.
Your boiler has stopped working because of a wiring issue or an electrical connection problem inside the main control panel.
Your boiler has detected an internal wiring problem or a connection issue that is preventing it from running safely.
Your boiler's internal computer has encountered a critical electronic failure and can no longer control the heating process safely.
Your boiler's main control computer has developed a serious internal error and can no longer safely operate the system.
Your boiler's internal computer has encountered a communication error or a serious hardware failure that prevents it from running safely.
Your boiler is still detecting a flame even after it has told the gas to turn off, which is a safety conflict that causes the system to shut down.
Your boiler has detected an internal electrical communication error, which means the main control board is likely faulty and cannot manage the heating process safely.
Your boiler has detected an internal electrical glitch or a faulty temperature sensor, causing it to shut down for safety.
Your boiler's internal computer has overheated, likely due to an electrical fault or a failing circuit board.
Your boiler's main control panel is having trouble communicating with the internal display screen, meaning you cannot see or adjust your heating settings.
Your boiler's internal computer has encountered a communication error or hardware failure and cannot operate safely.
Your boiler has stopped working because the water pressure is too low for it to run safely.
Your boiler is currently running at its maximum gas setting, which is usually a sign that it is trying to heat up quickly or has detected an internal issue with the gas flow control.
Your boiler is failing to start up because it cannot reliably ignite the gas flame required to provide heating or hot water.
Your boiler is struggling to accurately detect its current temperature, which has caused it to pause its heating operation as a safety precaution.
Your boiler is currently performing a factory calibration check to ensure the gas and air balance is set correctly for your home's fuel supply.
Your boiler is struggling to communicate with its internal control system, which has caused it to stop working to avoid potential damage.
Your boiler has detected that it is not correctly set up to run on the specific type of bottled gas you are using.
Your boiler is currently preparing to fire up the heating system and is circulating water through the pipes.
Your boiler is currently initiating its hot water system and the fan is running as part of the normal startup process.
Your boiler is currently trying to light itself to provide hot water but is still in the middle of its startup process.
Your boiler is currently running the internal fan to safely clear excess heat after finishing a hot water cycle, which is a normal part of the cooling process.
Your boiler is currently running its pump to safely move heat away from the system after making hot water, which is a normal part of the cooling-down process.
Your boiler is currently performing a routine check to keep a small amount of water hot inside the unit, ensuring your taps provide hot water quickly.
Your boiler is simply performing a routine safety check by clearing its internal ventilation before it fires up, which is a normal part of the start-up process.
Your boiler is currently just in the process of starting up its burner to heat your water.
Your boiler is currently performing a normal ignition process to provide hot water or heating.
Your boiler is currently cooling down after finishing a cycle, which is a normal part of its operation.
Your boiler is currently in a short waiting period to prevent it from switching on and off too frequently, which protects its internal components from excessive wear.
Your boiler is currently in standby mode because it has not received a request for heat from your wall thermostat or timer.
Your boiler is currently set to summer mode, which means it is turned off for household heating and is only active for hot water.
Your boiler has detected a potential issue with the fan's speed, which has triggered a safety feature to prevent the system from freezing up.
Your boiler is currently waiting for a signal from your thermostat or timer to tell it that the house needs heating or hot water.
Your boiler has temporarily stopped your underfloor heating because it detected that the water temperature in the pipes has become too hot for your floor surface.
Your boiler has temporarily paused to protect itself because the water inside is heating up or cooling down much faster than expected.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes