129 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Baxi Duo-tec Combi HE
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 →
Tap any card for details
Your boiler has reached the required temperature and is simply taking a normal rest before it needs to heat up again.
Your boiler has likely overheated or a sensor has detected a problem with the way water is moving through the system.
Your boiler has switched itself off because it has become too hot internally and needs to cool down for safety.
Your boiler has temporarily lost its flame and is attempting to restart itself automatically.
Your boiler has tried to light itself several times but cannot establish a flame, meaning your heating and hot water will not work.
Your boiler is experiencing a brief communication hiccup between its internal electronic parts and should fix itself automatically in a few moments.
Your boiler is unable to safely clear exhaust fumes from the system, which is preventing it from lighting to provide heat and hot water.
Your boiler has experienced a temporary computer glitch and is currently trying to reset itself to normal operation.
Your boiler's internal memory chip has developed a communication fault, meaning the control board no longer knows how to operate the unit correctly.
Your boiler has experienced a temporary communication hiccup and is currently trying to fix itself.
Your boiler has detected a general internal electrical fault and has stopped working to prevent further damage.
Your boiler has stopped working because the internal fan, which safely exhausts fumes, is not running correctly.
Your boiler is not receiving enough electrical power from the mains supply to operate safely.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler's internal computer has developed a fault and can no longer control the heating or hot water safely.
Your boiler's main internal computer has developed a fault and is no longer able to control the heating or hot water processes.
Your boiler has detected that water isn't moving through the system properly or there isn't enough water inside for it to heat up safely.
Your boiler has detected a faulty internal temperature sensor which means it cannot accurately monitor the water heat and has shut down for safety.
Your boiler has detected that its electrical wiring is connected incorrectly, meaning the power supply polarities are swapped.
Your boiler’s internal computer has developed a fault and can no longer control the heating or hot water safely.
Your boiler has become too hot and has shut itself down as a safety precaution, often because water cannot circulate properly.
Your boiler has too much water inside its system, which is putting excess pressure on the internal components.
Your boiler has stopped working because the water pressure inside the system has dropped below the minimum level required to operate safely.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler is overheating because the water isn't moving through the system properly, often caused by a pump failure or an air lock.
Your boiler hasn't been able to heat the water to a high enough temperature to kill off bacteria in the system.
Your boiler started to heat up but the flame went out unexpectedly while it was running.
Your boiler is failing to light the gas flame and has locked itself out for safety.
Your boiler has gone into a safety lockdown because the reset button was pressed too many times or held down for too long.
Your boiler's fan is not spinning correctly, which means it cannot safely clear exhaust gases and has shut down as a safety precaution.
Your boiler has detected an issue with how it moves air and exhaust gases through the system, preventing it from firing up safely.
Your boiler has detected a problem with how water is moving through the system, causing it to shut down to prevent overheating.
Your boiler has detected an issue with how air is moving through the system, meaning it cannot safely start the burner to provide heating or hot water.
Your boiler has detected that it is firing without enough water moving through it, or there is trapped air causing it to overheat rapidly.
Your boiler has detected a problem with its electrical safety grounding, which means it cannot safely confirm the presence of a flame.
Your boiler has switched itself off because it has become too hot to operate safely.
Your boiler has stopped working because it cannot communicate with the sensor that measures the temperature of the water returning to the unit.
Your boiler has detected a communication problem with the internal sensor that monitors water returning to the unit, preventing it from heating up correctly.
Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means there is a circulation problem or a sensor error.
Your boiler is struggling to keep a steady flame going and has shut down after failing to stay lit several times.
Your boiler's fan is not spinning at the right speed to safely clear away fumes, which may be caused by strong winds outside or a mechanical fault.
Your boiler has detected that water is flowing the wrong way or overheating in the wrong place, causing it to shut down for safety.
Your boiler has stopped working because water is not moving through the system properly or a sensor has lost its connection.
Your boiler has shut down because it has detected that the internal exhaust gases are becoming too hot, which is often caused by water not flowing through the system properly.
Your boiler is simply notifying you that the reset button was recently used and it is restarting itself.
Your boiler has detected that the water pressure is too low for it to operate safely and has shut itself down as a precaution.
Your boiler's computer system has encountered a major internal error or has timed out, meaning it can no longer communicate with its internal components to operate safely.
Your boiler's electronic brain is unable to talk to the valve that controls the gas supply, meaning the system cannot safely light the flame.
Your boiler's computer brain is confused because a physical internal setting has been moved or detected incorrectly.
Your boiler's internal computer settings have been changed or misconfigured, meaning it doesn't currently know which model it is supposed to be.
Your boiler's internal computer settings have been changed or are set incorrectly, which is preventing it from starting up properly.
Your boiler is having trouble communicating with an external control, such as your room thermostat or timer, due to a connection issue.
Your boiler is having trouble communicating with your thermostat or wireless controls, meaning it cannot receive the command to turn on.
Your boiler has lost communication with its gas control unit and cannot safely ignite to provide heating or hot water.
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit due to a faulty internal sensor or wiring.
Your boiler has lost its connection to the sensor that monitors water temperature, causing the system to shut down for safety.
Your boiler has shut down because it is overheating, often caused by a lack of water moving through the system or a blockage.
Your boiler has detected a problem with the sensor that monitors exhaust gases, causing the system to lock out for safety.
Your boiler has detected an issue with the sensor that monitors exhaust gases, meaning it has shut down for safety purposes.
Your boiler has shut down because it is getting too hot inside, which is likely caused by water not moving through the system correctly or a faulty internal sensor.
Your boiler has shut down because it has detected it is getting too hot, which is usually caused by water not moving through the system correctly.
Your boiler is struggling to ignite the flame, which is likely due to an issue with your gas supply or a component that handles the ignition process.
Your boiler detects a flame when there shouldn't be one, or the internal parts are becoming too hot for the system to operate safely.
Your boiler has stopped working because the fan that helps remove waste gases is stuck or broken, causing the system to shut down for safety.
Your boiler has detected a serious internal problem with how it receives or manages gas, meaning it cannot safely light itself to provide heating or hot water.
Your boiler's internal thermometer has stopped working correctly, so the system is staying off for safety because it cannot monitor the water temperature.
Your boiler has become too hot internaly and has shut down as a safety precaution to prevent damage.
Your boiler is struggling to push water around the system, which is likely caused by trapped air blocking the pipes or radiators.
Your boiler's internal computer has developed a fault and can no longer control the heating system safely.
Your boiler has failed to light, which could be caused by air trapped in the system or a temporary interruption to your gas supply.
Your boiler has lost its electrical connection to the gas control valve, meaning it cannot safely ignite to provide heating or hot water.
Your boiler has lost connection or is receiving incorrect information from the sensor located on the outside of your house that helps it adjust to the weather.
Your boiler has detected that water is not circulating properly through the system, which is preventing it from firing up for safety.
Your boiler has detected that a internal safety switch is stuck, preventing it from starting up correctly to provide heating or hot water.
Your boiler's electronic control board is struggling to communicate with the internal gas valve, meaning the system cannot safely light the flame.
Your boiler has lost its connection to the sensor that monitors the temperature of your radiators, causing the system to stop working as a safety precaution.
Your boiler has detected a problem with how it releases exhaust gases or a sensor error, causing it to shut down for safety.
Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your radiators.
Your boiler has lost the ability to measure the temperature of your hot water, which usually means your taps will only run cold.
Your boiler is not burning gas correctly and has shut down to prevent the build-up of dangerous fumes.
Your boiler is struggling to detect when you turn on a hot tap, meaning you might have inconsistent or no hot water.
Your boiler has lost its electronic settings and needs to be professionally reconfigured to ensure it is burning gas safely and efficiently.
Your boiler is struggling to monitor the water pressure correctly, which is preventing it from running safely.
Your boiler's internal computer brain is having trouble talking to the other electrical parts inside the unit, preventing it from starting up.
Your boiler has detected an issue with the air and gas mix while trying to automatically adjust its settings to ensure it is burning fuel safely.
Your boiler's internal computer brain is having trouble keeping time, which is preventing it from running properly.
Your boiler is struggling to move water around the system properly, which is causing it to stop running to prevent overheating.
Your boiler has likely overheated, causing a safety switch to trip and shut the system down to protect itself.
Your boiler has too much water inside it, which has caused the system to shut down for safety.
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Your boiler has stopped working because the water pressure inside the system has dropped too low.
Your boiler is struggling to move water around the system correctly, which is causing it to overheat and shut down for safety.
Your boiler has tried to light several times but the flame keeps going out, causing the system to lock itself for safety.
Your boiler is struggling to keep its flame lit during its automated setup process and has locked itself out for safety.
Your boiler has sensed that the exhaust gases are getting too hot and has shut down as a safety precaution.
Your boiler has shut down because the exhaust gases have become too hot, which is a safety measure to prevent damage to the system.
Your boiler has failed to light because it either cannot get enough gas or it cannot detect the flame it has sparked.
Your boiler has failed to ignite after several attempts because it cannot detect a steady flow of gas or a flame.
Your boiler has lost its gas supply or cannot detect the gas coming in, causing it to shut down for safety.
Your boiler has noticed that water is not circulating properly through the system, possibly due to a blockage or a pump issue.
Your boiler has detected a problem with the fan that clears exhaust gases, preventing the system from starting up for safety reasons.
Your boiler has detected a problem with the fan that safely removes exhaust gases, meaning it cannot start up for safety reasons.
Your boiler's hot water sensor is not working correctly, meaning your hot water may be too hot, cold, or not working at all.
Your boiler's internal sensor that monitors water pressure is sending an incorrect signal to the control board, preventing it from heating your home safely.
Your boiler's internal computer has developed a fault and can no longer control the heating or hot water safely.
Your boiler's internal computer has encountered a generic error and has locked itself for safety, usually because it cannot detect exactly why it stopped working.
Your boiler has detected that water is not circulating correctly through the system before the burner ignites, often caused by a temporary blockage or air in the pipes.
Your boiler is overheating because water isn't moving through the system properly, causing it to shut down to prevent damage.
Your boiler is having trouble with the electrical supply because the power frequency doesn't match what the system needs to run.
Your boiler's hot water sensor has failed or is giving an incorrect reading, meaning the system cannot accurately monitor the temperature of the water coming out of your taps.
Your boiler thinks a flame is burning even though it hasn't been told to light, so it has shut down for safety.
Your boiler is not receiving enough electrical power to run safely, likely due to an issue with your home's electricity supply or the boiler's internal control board.
Your boiler has detected a sudden drop in water pressure and is briefly checking if the system is stable enough to keep running.
Your boiler has lost its connection with the internal gas control system, meaning it cannot safely ignite to provide heating or hot water.
Your boiler is overheating because water isn't moving through the system quickly enough or the sensors are reading incorrect temperatures.
Your boiler is overheating or water isn't moving through the system fast enough, causing it to shut down for safety.
Your boiler has detected that the water inside it is getting too hot too quickly, likely because the water isn't moving through the system as it should.
Your boiler has stopped working because water is not moving through the system properly or a sensor is giving an incorrect reading.
Your boiler is shutting down because it is heating up too quickly while trying to provide hot water, usually because the water cannot flow through the system properly.
Your boiler’s main control board has lost its internal settings or was not properly set up, meaning it currently doesn't know how to operate.
Your boiler's computer memory has a temporary glitch or incorrect setting, causing it to pause while it tries to verify its configuration.
Your boiler's computer system has encountered a temporary communication glitch or a setting error that is preventing it from running correctly.
Your boiler has detected that the water pressure is incorrect or there is a possible leak within your heating system.
Your boiler has stopped working because its internal sensors are unable to talk to the main control board correctly.
Your boiler's internal computer brain is having trouble talking to its other components, which has caused the system to stop working for safety.
Your boiler has lost its flame while it was running, which means it cannot heat your water or radiators.
Your boiler is not receiving any electrical power and the display screen is completely blank.
Your boiler has failed to ignite several times and has locked itself out for safety reasons.
Your boiler has detected an internal communication problem between its electronic control boards due to a wiring issue.
BoilerFaultCodes