97 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Genus Premium EVO
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler is trying to start but cannot get the flame to stay lit, so it has safely shut itself down to avoid wasting fuel.
Your boiler has detected that water is not flowing through the system correctly, so it has shut down to protect itself from overheating.
Your boiler has automatically turned itself off because the water inside it has become dangerously hot.
Your boiler has detected an internal error during its startup safety check and has stopped working to prevent any potential risks.
Your boiler has stopped working because it couldn't light the burner to create heat, most likely due to an issue with its gas supply.
Your boiler has stopped working because the water pressure is too low for it to operate safely.
Your boiler has shut down because it has detected it is getting too hot, which is usually caused by water not circulating properly through the system.
Your boiler is struggling to keep a flame lit during its normal cycle, causing it to shut down for safety.
Your boiler has detected that water is not moving through the system correctly, which has caused it to stop working to prevent overheating.
Your boiler is unable to move water around the system, which is preventing it from heating your home or providing hot water.
Your boiler is still detecting a flame after it has supposedly turned the gas off, which is a safety concern that requires a professional inspection.
Your boiler thinks it sees a flame before it has even started the ignition process, causing it to shut down for safety.
Your boiler has detected that water is not moving through the system properly, which has caused it to shut down to prevent overheating.
Your boiler has detected that a internal water safety switch is stuck in the 'on' position, preventing the system from starting its normal cycle.
Your boiler has stopped working because the fan that helps remove waste gases is not spinning or communicating correctly with the system.
Your boiler's computer board has encountered a software or communication error and is unable to manage the heating process safely.
Your boiler's internal computer has encountered a communication error which is preventing it from running properly.
Your boiler's internal computer has encountered a communication error or software glitch that is preventing it from monitoring the system's safety and operation.
Your boiler is failing to light itself after several tries and has locked out for safety.
Your boiler has tried to fire up several times but isn't detecting a rise in water temperature, so it has shut down to prevent damage.
Your boiler has detected that the water inside is getting dangerously hot and has shut down to prevent damage.
Your boiler is repeatedly struggling to stay lit and has locked itself out for safety after multiple failed attempts to ignite.
Your boiler is still detecting a flame even after it has tried to shut off the gas, which is a significant safety concern.
Your boiler thinks it sees a flame even though it hasn't started the ignition process yet, which is causing it to shut down for safety.
Your boiler has stopped working because it cannot detect that water is moving through the system properly.
Your boiler has detected that water is still moving, or a sensor thinks it is, even though the pump has stopped.
Your boiler has stopped working because the fan that helps remove waste gases is not spinning or communicating correctly with the system.
Your boiler's computer is having trouble processing information and may struggle to control your heating system properly.
Your boiler has detected that the water inside the system is getting dangerously cold and has automatically fired up to prevent the pipes from freezing.
Your boiler is notifying you that the burner is currently firing specifically to heat the water inside your external storage cylinder.
Your boiler has detected a failure in its internal safety systems and has shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler is operating normally and is currently running to provide central heating to your home.
Your boiler is simply showing you the target room temperature you have selected while you are adjusting the heating control knob.
Your boiler is currently heating water for your taps or shower, and the burner is active as intended.
Your boiler has stopped working because there is not enough water inside the system to operate safely.
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving it to heat your home.
Your boiler has detected a faulty temperature sensor on the heating outlet pipe, which is preventing the system from monitoring the water temperature correctly.
Your boiler has detected a faulty sensor on the pipe that returns water from your radiators, preventing it from monitoring temperatures correctly.
Your boiler has stopped heating because a safety sensor has detected that your underfloor heating system is getting too hot or there is a break in the connection to its thermostat.
Your boiler's internal computer has encountered a communication error or software glitch that is preventing it from running properly.
Your boiler's internal computer is receiving confusing or conflicting information from the sensors that monitor the water temperature leaving and returning to the system.
Your boiler has stopped working because the flame has failed to stay lit or is not being detected during operation.
Your boiler has detected an issue with the air flow or ventilation, causing it to stop running as a safety precaution.
Your boiler's main burner is not firing correctly, which means your heating and hot water will not work.
Your boiler has detected that it is getting dangerously hot even while it isn't supposed to be running, causing it to shut down for safety.
Your boiler has detected a problem with how it clears exhaust fumes, causing it to shut down for safety.
Your boiler has lost its connection to the sensor that monitors hot water temperature, which means it cannot safely heat water for your taps.
Your boiler's temperature sensor for hot water has developed an electrical fault, meaning the system cannot safely gauge how hot your water is and has stopped heating it.
Your boiler has lost communication with the temperature sensor that monitors your underfloor heating, preventing that system from running safely.
Your boiler thinks a flame is present even though it hasn't turned the gas on, causing it to shut down for safety.
Your boiler has detected that the electrical wiring coming into the unit is connected incorrectly, which is a safety conflict between the live and neutral wires.
Your boiler is struggling because the electrical supply to the unit is unstable or incorrect, preventing it from running safely.
Your boiler has stopped working because it cannot correctly detect if the burner is lit, likely due to a faulty or damp electrical sensor inside the unit.
Your boiler has lost connection with the sensor that monitors the temperature of the water leaving the unit, causing the system to shut down for safety.
Your boiler has lost its connection to the sensor that monitors the temperature of the water returning from your radiators.
Your boiler has detected a problem with the internal sensor that monitors the temperature of the water leaving the unit to heat your home.
Your boiler has detected an electrical fault with the sensor that monitors water returning from your radiators, preventing the system from operating safely.
Your boiler has tried to start five times without success and has locked itself out for safety reasons.
Your boiler has detected an unusually high temperature reading while it isn't even running, which usually points to a faulty internal sensor.
Your boiler is unable to measure the temperature of the water going to your taps, which usually means it will stop providing hot water for safety reasons.
Your boiler's hot water sensor has failed, meaning it can no longer accurately measure how hot your water is and has stopped heating it as a safety precaution.
Your boiler has lost connection with the sensor that monitors the temperature of your underfloor heating, which may prevent that specific zone from warming up correctly.
Your boiler's safety system thinks it can see a flame even though the gas should be turned off, so it has shut down for safety.
Your boiler has detected that the electrical wiring coming from your home’s power supply is connected incorrectly, which is preventing it from starting up safely.
Your boiler is struggling to operate because the electrical power coming into your home is unstable or not at the correct frequency.
Your boiler has detected an electrical fault with the sensor that checks for a flame, causing the system to shut down for safety.
Your boiler has lost connection with the sensor that monitors the temperature of the water leaving for your radiators, causing the system to shut down for safety.
Your boiler has stopped working because it can no longer monitor the temperature of the water coming back from your radiators.
Your boiler has detected a fault with the sensor that monitors the temperature of the water heading to your radiators, meaning the system cannot run safely or effectively.
Your boiler has stopped working because a sensor that monitors the temperature of the water returning from your radiators has developed an electrical fault.
Your boiler's internal computer has encountered a critical error and can no longer communicate with the rest of the system.
Your boiler is failing to light the burner, meaning it cannot provide you with any heating or hot water.
Your boiler has detected that there is not enough water pressure flowing through the system to heat your home safely.
Your boiler has detected that it is running much too hot and has automatically shut itself down to prevent any damage or safety issues.
Your boiler has stopped working because it cannot detect enough water pressure circulating inside the system.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler is displaying a setting menu related to its heating power level rather than a mechanical fault.
Your boiler is intentionally pausing for a short time before starting the central heating to prevent unnecessary cycling and improve efficiency.
Your boiler is struggling to establish a stable flame because the starting power level isn't sufficient for the ignition process to complete correctly.
Your boiler has detected that the water pump is not running correctly, so it has safely shut itself down to prevent damage to the system.
Your boiler tried to light the burner but couldn't detect a flame, causing it to stop for safety.
Your boiler is struggling to light its flame after two tries, which means it cannot heat your home or water.
Your boiler is struggling to detect the temperature of your hot water, which means it cannot provide consistent or safe water for your taps and showers.
Your boiler has lost the ability to monitor the temperature of your hot water because a sensor has malfunctioned, which will likely prevent you from getting warm water at your taps.
Your boiler is starting the combustion process, but the flame is failing to stay stable or is drifting away from the burner, causing the system to shut down for safety.
Your boiler is struggling to read the temperature of the external hot water storage cylinder, which may result in a lack of hot water.
Your boiler has lost connection with the sensor that monitors the temperature of your hot water tank, meaning it cannot safely heat your water.
Your boiler's hot water storage tank has reached an unsafe temperature and has shut down to prevent damage.
Your boiler has lost signal from the temperature sensor located outside your home, meaning it doesn't know how hard it needs to work to match the outdoor weather.
Your boiler has lost the connection to its outdoor temperature sensor, which helps it run efficiently based on the weather outside.
Your boiler has lost communication with its wall-mounted thermostat, meaning it cannot accurately tell what temperature your rooms are.
Your boiler's main internal computer has detected a problem while trying to ignite and has shut itself down for safety.
Your boiler has detected that the water leaving the unit to heat your radiators is at an incorrect temperature, which usually indicates an issue with the sensor or water flow.
Your boiler has detected an issue with the sensors that monitor the temperature of the water returning from your radiators.
Your boiler is displaying the current temperature of the hot water flowing to your taps rather than an actual error.
Your boiler is struggling to detect the flame it needs to stay lit safely, which is preventing the system from heating your home or water.
Your boiler has detected that water is not circulating correctly through the main system, causing it to stop for safety.
BoilerFaultCodes