67 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
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Your boiler is notifying you that it is due for its regular annual service or scheduled maintenance check-up.
Your boiler is struggling to light its burner or cannot detect that a flame has been successfully lit, preventing it from heating your water.
Your boiler has failed to light the flame, which means your heating and hot water will not work until the system is reset or the gas supply is restored.
Your boiler has switched itself off because it has detected that the water inside has become dangerously hot.
Your boiler has detected that the exhaust gases are getting too hot, or a safety fuse has blown to prevent the unit from overheating.
Your boiler has detected that either the water pressure is too low or the pump is struggling to move water around the system.
Your boiler has stopped working because water is not moving through the system correctly, which could be due to a blockage, trapped air, or a pump issue.
Your boiler's central heating sensor has stopped working correctly, which means the system cannot safely monitor the temperature of the water going to your radiators.
Your boiler's temperature sensor for hot water has stopped working correctly, meaning your taps and shower may not produce hot water.
Your boiler's temperature sensor for hot water has stopped working properly, meaning your taps and showers may run cold or at inconsistent temperatures.
Your boiler is detecting a flame even when it hasn't been told to light one, which is causing it to shut down for safety.
Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.
Your boiler has detected a fault with the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety.
Your boiler has detected that the water pressure inside the system is too low for it to operate safely.
Your boiler's internal computer has lost its settings and needs to be set up again by a professional.
Your boiler has shut itself down because it detected that the internal water temperature has become too hot to operate safely.
Your boiler is failing to detect a flame after it has ignited, causing the system to shut down for safety.
Your boiler has detected an issue with the electrical power supply coming from the mains, meaning the electricity is not stable enough for the boiler to operate safely.
Your boiler's internal computer has developed a fault and is struggling to communicate with the rest of the system.
Your boiler is working normally, but it is displaying a reminder that its annual safety check and service are now due.
Your boiler has detected that water is not moving around the system properly, which has caused it to shut down to prevent overheating.
Your boiler's computer control board has developed an internal electrical fault and is unable to manage the system safely.
Your boiler's internal computer has developed a fault and can no longer control the heating system correctly.
Your boiler's internal computer has encountered a critical error and cannot communicate with the rest of the system.
Your boiler's internal computer has developed a serious communication fault and can no longer control the heating or hot water functions.
Your boiler has entered a lockout state to prevent further damage or safety risks, usually following a failed ignition or a recurring internal error.
Your boiler has tried to light several times but failed, so it has shut itself down for safety.
Your boiler has tried to light several times but failed, so it has locked itself out for safety.
Your boiler has switched itself off because it has detected that the water inside has become or is becoming too hot.
Your boiler has shut down because it has detected it is getting too hot, triggering a safety switch to prevent damage.
Your boiler's main control board has encountered an internal electronic failure and is unable to manage the heating process.
Your boiler has experienced a general safety lockout and requires a manual restart to try and clear the error.
Your boiler has detected that there is either not enough water in the system or the water isn't moving through the pipes correctly.
Your boiler has detected that there is either not enough water in the system or the water isn't moving through the pipes properly.
Your boiler has stopped working because it can no longer accurately measure the temperature of the water inside the system.
Your boiler has detected a problem with the fan that safely removes exhaust gases, meaning the system has shut down for safety.
Your boiler is having trouble measuring the temperature of your hot water, which usually results in the water being stone cold or not reaching the right temperature.
Your boiler's central heating sensor has stopped working correctly, which means the system cannot accurately measure how hot the water is for your radiators.
Your boiler has detected that the water pressure is either too low or the sensor that monitors it is not working correctly, causing the system to shut down for safety.
Your boiler's hot water sensor has failed, meaning the system doesn't know how hot your water is and will likely stop producing hot water for showers and taps.
Your boiler is struggling to communicate with the outside temperature sensor, which helps it run efficiently.
Your boiler's outside temperature sensor is either broken or sending a wrong signal, which affects how efficiently the heating adjusts to the weather.
Your boiler has detected that a sensor monitoring the temperature of the exhaust gases is not working correctly, causing the system to shut down for safety.
Your boiler has detected that a sensor monitoring exhaust gas temperatures is faulty or has disconnected, causing the system to shut down for safety.
Your boiler has detected a blockage in the condensation drainage pipe or a fault with its internal sensing system, causing it to shut down for safety.
Your boiler has shut down because it has detected that the exhaust gases are becoming dangerously hot, which is a safety feature to prevent damage to the flue system.
Your boiler is failing to detect a flame, which means it cannot light safely to provide heating or hot water.
Your boiler has failed to light the gas or cannot tell that the flame is burning, causing it to shut down for safety.
Your boiler has sensed a problem with the internal sensor that monitors the temperature of the water returning from your radiators.
Your boiler has detected that a sensor monitoring the temperature of the water coming back from your radiators is not working correctly.
Your boiler has detected that the water is getting too hot too quickly because it isn't circulating through the system properly.
Your boiler has sensed that water is becoming too hot too quickly, usually because it cannot circulate correctly through your radiators or pipes.
Your boiler has detected that water isn't moving through the system properly or there is a lack of water, causing it to overheat and lock itself for protection.
Your boiler has stopped working because water isn't moving through the system properly, causing it to overheat.
Your boiler has detected that water isn't moving through the system properly or there is a lack of water pressure, causing it to overheat and lock itself for 10 minutes.
Your boiler has stopped working because water is not moving through the system properly or it has become dangerously hot.
Your boiler is having trouble measuring the temperature of the cold water coming in, which may affect how well it heats your hot water.
Your boiler's hot water sensor has stopped working correctly, which may cause issues with the temperature of your baths and showers.
Your boiler has detected that the main heat exchanger is getting too hot or is not circulating water correctly, causing the system to shut down for safety.
Your boiler is failing to detect a flame, which means it cannot fire up to provide heating or hot water.
Your boiler has shut down because it has detected an electrical connection issue or an internal wiring conflict within its control system.
Your boiler has lost power or hasn't had its model type correctly configured in the internal computer.
Your boiler is notifying you that the water pressure has dropped too low and the system needs to be topped up.
Your boiler has reached an excessively high temperature while trying to provide hot water and has shut down as a safety precaution.
Your boiler has detected an issue with the sensor that monitors the temperature of the cold water coming into the unit, which can affect its ability to heat your water correctly.
Your boiler has stopped working because the water pressure in the central heating system is too low.
Your boiler is notifying you that it is due for its annual safety check and routine service.
BoilerFaultCodes