151 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: 240 Ri / 240 i
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 detected a critical internal error with its electronics or air management system and has disabled itself for safety.
Your boiler is currently stuck in a manual test mode typically used by engineers, which is preventing it from running its normal heating cycles.
Your boiler has been left in a manual testing mode after a recent service, which means it isn't running in its normal automatic setting.
Your boiler's electronic control parts do not match each other, preventing the system from starting up.
Your boiler's internal computer module is either the wrong version for this model or has been incorrectly configured, preventing the system from starting.
Your boiler has lost its identity because a small electronic chip containing its software settings has failed or become loose.
Your boiler is currently working correctly and is simply indicating that it is in central heating mode.
Your boiler is working normally and is currently heating up your radiators.
Your boiler is simply notifying you that it is currently preparing or providing hot water for your taps or shower.
Your boiler is currently working as it should by focusing its energy on providing hot water to your taps.
Your boiler is working normally and is simply waiting for a command from your thermostat or timer to start heating.
Your boiler is taking a short, temporary break to prevent the system from switching on and off too frequently, which protects the internal components.
Your boiler is currently in standby mode and is simply waiting for a request from your thermostat or hot water tap to start working.
Your boiler is working correctly but is currently sitting in standby mode because your thermostat or hot water tap hasn't asked it to turn on.
Your boiler is currently taking a short break because it has reached the required temperature and is waiting for the water to cool down slightly before firing up again.
Your boiler has stopped because the water inside it has become hotter than the temperature you have requested.
Your boiler is currently running at maximum power for a service test and will not respond to your normal thermostat settings until this mode is turned off.
Your boiler is currently set to a manual testing mode used by engineers to check emissions, which overrides normal heating controls.
Your boiler has shut down because it is overheating too quickly, which usually means water is not circulating through the system properly.
Your boiler has switched itself off to prevent overheating because the water pressure is likely too low.
Your boiler has recorded that a professional tester or diagnostic tool was plugged into the control system while it was in a specific error history mode.
Your boiler is failing to light properly or stay lit, meaning your heating and hot water have stopped working.
Your boiler thinks a flame is burning even when it shouldn't be, which is a safety conflict that prevents it from starting up.
Your boiler's internal computer brain is using software that doesn't match its hardware, preventing the system from starting up.
Your boiler has started up but cannot detect the water getting any hotter, so it has shut down to prevent overheating.
Your boiler is temporarily limiting its power output because it has reached its target temperature and is waiting for the heating system to catch up.
Your boiler is currently running a self-diagnostic check to ensure all internal parts are working correctly.
Your boiler is temporarily adjusting its power output to reach the correct temperature and should return to normal operation shortly.
Your boiler is simply performing its normal startup routine and checking everything is ready before it lights the flame.
Your boiler has detected an internal electrical problem with the component that controls the gas flow, causing it to shut down for safety.
Your boiler thinks a hot water tap is still running and is waiting for it to be turned off before it can provide heating.
Your boiler has temporarily paused the hot water heating process to prevent the system from switching on and off too frequently, which protects the internal components from unnecessary wear.
Your boiler is still detecting a flame even after it has been told to shut off the gas, which is a safety fault that requires a professional inspection.
Your boiler has detected an unstable electrical supply or an internal fault with its control board that is preventing it from running safely.
Your boiler is not receiving enough electrical power from the mains supply to run safely and has shut down as a precaution.
Your boiler's computer brains are not communicating correctly because the internal memory chip doesn't match the main control board.
Your boiler's internal computer chip is either loose or doesn't match the control board, preventing the system from starting up.
Your boiler's temperature sensors are receiving conflicting readings, which usually means a sensor is broken or out of place.
Your boiler has lost its internal connection to the smart controls or sensors, meaning the parts aren't talking to each other correctly.
Your boiler has stopped working because the water pressure is too low for it to operate safely.
Your boiler is unable to track the temperature of your hot water, meaning you likely have no hot water or it is not heating up correctly.
Your boiler's hot water tank sensor is failing or disconnected, which means the system cannot accurately monitor or heat your water supply.
Your boiler is struggling to accurately gauge the weather outside, which may cause it to run less efficiently or heat your home incorrectly.
Your boiler has lost the ability to monitor its own water pressure, which has caused it to shut down as a safety precaution.
Your boiler is struggling to understand how cold it is outside, which may cause your heating to be less efficient or run at the wrong temperature.
Your boiler has detected an electrical fault with its internal thermometer, meaning it cannot accurately measure the water temperature to safely provide heating or hot water.
Your boiler has lost its connection with the internal sensor that monitors water temperature, meaning it cannot safely regulate heat and has likely stopped working.
Your boiler has detected an electrical fault with an internal temperature sensor, preventing it from safely heating your home or water.
Your boiler has lost communication with its internal temperature sensor, preventing it from heating your water and radiators safely.
Your boiler is failing to detect a flame, which means it cannot safely stay lit to provide heating and hot water.
Your boiler's control system is unable to communicate with the gas supply valve, meaning the boiler cannot ignite for heating or hot water.
Your boiler has detected an issue with the fuel supply control system, meaning it cannot safely regulate the gas flow to keep the burner lit.
Your boiler has lost its flame while running and has shut down as a safety precaution because it cannot maintain a steady supply of gas or a spark.
Your boiler's internal configuration chip is incorrect or faulty, preventing the system from recognizing which specific model it is.
Your boiler is struggling to keep a flame lit, which means it will stop providing heat and hot water until the issue is resolved.
Your boiler is struggling to detect a flame and is failing to stay alight properly, meaning your heating and hot water might be intermittent or unavailable.
Your boiler has stopped working because its internal sensors are sending incorrect information or have been disconnected.
Your boiler is struggling to push water through the heating system, causing it to overheat and shut down for safety.
Your boiler has stopped working because the water inside is getting too hot too quickly, which usually means it can't circulate water through your radiators properly.
Your boiler is overheating because the water inside it is getting too hot too quickly, often caused by a blockage or a pump that isn't moving the water fast enough.
Your boiler is shutting down because it has detected a sudden, large temperature difference between the water entering and leaving the system, which usually means water isn't circulating properly.
Your boiler has detected that the water pressure in your pipes is falling too quickly, which usually means there is a leak somewhere or a component is failing to hold pressure.
Your boiler has detected that the water pressure is too low for it to run safely, likely due to a minor leak or air trapped in your radiators.
Your boiler has detected that there is not enough water circulating, likely because the pump is stuck or there is an internal leak affecting the system pressure.
Your boiler's water pump has stopped moving or is struggling to circulate water because there is air trapped inside the system.
Your boiler has detected an electrical fault with the sensor that monitors exhaust gases, causing the system to shut down for safety.
Your boiler's temperature sensor for hot water has stopped working correctly, meaning your taps might not get hot.
Your boiler has lost its connection to the external heating controls, meaning it cannot receive instructions on when to turn on or off.
Your boiler is struggling to operate because it is receiving an unsteady or insufficient supply of electricity.
Your boiler's internal computer is having trouble communicating with a small identity chip that tells it which model it is.
Your boiler's internal computer has encountered a critical error and cannot communicate properly to manage the heating process.
Your boiler has detected that the fan or air supply has cut out while it was running, causing the system to shut down for safety.
Your boiler's internal computer has developed a fault and can no longer communicate with the heating components, preventing the boiler from firing up.
Your boiler has been running for a full 24 hours without a break and needs to turn off briefly to perform a safety self-test.
Your boiler has stopped working because the fan that clears out exhaust gases is not spinning fast enough or has lost power.
Your boiler has stopped working because the fan is spinning at the wrong speed, which means it cannot safely clear exhaust fumes.
Your boiler's fan is not spinning fast enough to safely clear out exhaust fumes, causing the system to shut down for safety.
Your boiler has detected that the internal fan, which safely clears away waste gases, is not spinning.
Your boiler has stopped working because the internal fan is spinning too slowly to safely clear out exhaust fumes.
Your boiler has shut down because the internal fan, which safely exhausts fumes, has stopped spinning while the heating was running.
Your boiler has lost communication with the weather sensor located outside your home, which helps it adjust the heating temperature automatically.
Your boiler has stopped working because the water level inside the system has dropped too low to operate safely.
Your boiler has stopped working because it cannot circulate water through the system properly.
Your boiler is having trouble measuring the temperature of the water returning to the system, which is preventing it from heating your home correctly.
Your boiler has lost its connection to the sensor that monitors water returning from your radiators, causing the system to stop working as a safety precaution.
Your boiler has shut down because a safety device or external control has detected a problem and cut the connection to the system.
Your boiler is overheating because the water inside is heating up faster than it can be circulated away.
Your boiler has detected that parts of the system are getting too hot too quickly, likely because water isn't moving through the unit properly.
Your boiler has shut down because it thinks the water returning to it is dangerously hot, which usually means the water isn't circulating properly through your radiators.
Your boiler is overheating because water is not moving through the system quickly enough, making the temperature rise too fast.
Your boiler's temperature sensor has failed or has a loose connection, meaning the system can no longer accurately monitor how hot the water is going to your radiators.
Your boiler's internal sensor that monitors water temperature has developed an electrical fault, causing the system to shut down for safety.
Your boiler has lost connection with the sensor that monitors the temperature of the water leaving the unit, causing it to shut down for safety.
Your boiler has stopped working because it cannot communicate with the part that monitors the temperature of the water flowing to your radiators.
Your boiler has detected a faulty internal temperature sensor, which means it cannot tell how hot the water is and has stopped running as a safety precaution.
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 the internal water temperature has become too hot for the system to operate safely.
Your boiler has switched itself off because it has detected that the internal water temperature has become too high, often caused by a blockage or lack of water pressure.
Your boiler has detected that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent internal damage.
Your boiler has sensed that it is getting too hot and has shut itself down to prevent internal damage.
Your boiler has shut down because it has detected an unsafe level of overheating or a critical failure in its primary safety sensor.
Your boiler has shut down because a safety sensor has detected that the internal components or exhaust gases have become dangerously hot.
Your boiler has shut down because it has detected that the water inside it is getting much too hot and could be overheating.
Your boiler has shut down because it has detected it is getting too hot, likely due to a circulation problem or a faulty internal sensor.
Your boiler has shut down because it has detected that the water temperature is becoming dangerously hot, which usually means the water isn't moving through the system properly.
Your boiler has shut down because it can no longer safely monitor the temperature of the exhaust gases leaving the system.
Your boiler has stopped working because it cannot light the burner, likely due to a temporary interruption in the gas supply or a component failure.
Your boiler is failing to light the gas burner or has lost its flame while running, which means it cannot provide heat or hot water.
Your boiler has lost its flame while it was running and has safely shut down to prevent any issues.
Your boiler has lost its connection to the gas valve, meaning it cannot ignite to provide heat or hot water.
Your boiler's internal computer brain is struggling to communicate or start correctly, stopping the system from providing heat and hot water.
Your boiler is struggling to light the gas flame properly and has timed out for safety.
Your boiler's computer system has detected a software or internal electronics failure and has stopped working for safety.
Your boiler is struggling to move water around the system correctly, causing it to throttle its power back to prevent overheating.
Your boiler's internal computer or its communication module has developed a fault and can no longer control the heating process.
Your boiler has experienced an internal electrical communication error, meaning it cannot process the signals needed to start up safely.
Your boiler's internal computer has encountered a software or communication glitch and has stopped working to protect itself.
Your boiler has detected an internal electrical communication error between the main controller and the gas supply unit, meaning it cannot safely ignite.
Your boiler's main internal computer has developed a communication fault and can no longer control the heating process safely.
Your boiler’s internal computer has developed a fault and can no longer communicate with the main controls, causing the system to shut down for safety.
Your boiler's internal computer has developed a fault and can no longer communicate with the main control system.
Your boiler's internal computer or control board has encountered a serious communication error and cannot operate for safety reasons.
Your boiler's internal computer has encountered a critical error and can no longer control the heating process safely.
Your boiler's internal computer is having trouble communicating with its temperature sensors, which means it cannot safely monitor the water temperature and has shut down as a precaution.
Your boiler's internal computer has developed a serious communication error or electrical fault that is preventing the burner from lighting.
Your boiler's internal computer has developed a serious communication fault and can no longer control the heating process safely.
Your boiler's internal computer has developed a communication fault and can no longer safely control the flame.
Your boiler's internal computer has encountered a critical error and can no longer communicate with the main controls, causing the system to shut down.
Your boiler's internal computer or its wiring connections have developed a fault, meaning the system cannot communicate properly to manage the heating process.
Your boiler's internal computer or control center has developed an electrical fault and is unable to communicate with the rest of the system.
Your boiler thinks it sees a flame even when it should be turned off, which is causing it to shut down for safety.
Your boiler thinks it sees a flame even though it hasn't actually started the burner yet, which is preventing it from firing up safely.
Your boiler has experienced a temporary loss of power or a momentary electrical flicker that has interrupted its normal operation.
Your boiler is still detecting a flame even though it has tried to turn the gas off, which is a safety conflict that requires a professional inspection.
Your boiler thinks it still sees a flame even though the heating has been turned off.
Your boiler has detected a potential internal gas leak during its safety checks and has shut down to keep your home safe.
Your boiler has detected a potential internal gas leak within the valve system and has shut down as a safety precaution.
Your boiler has entered a temporary lock-out mode because the reset button was pressed by accident or for too long.
Your boiler has lost its connection to the mains electricity supply or has experienced a sudden power interruption.
Your boiler has detected that the water pressure is too low for it to work properly, which will prevent it from providing full heating or hot water.
Your boiler is repeatedly restarting itself because it has detected an internal electronic error or a problem with its power supply.
Your boiler is currently idle because your thermostat or timer isn't telling it that you need any heating or hot water.
Your boiler is working normally and is currently heating up to provide warmth for your radiators.
Your boiler is overheating because the water temperature is climbing far too quickly, causing it to shut down to prevent damage.
Your boiler has no power going to it, causing the display and indicator lights to remain completely dark.
Your boiler is currently attempting to restart itself, likely after it detected an issue or you pressed the reset button.
Your boiler is currently running a self-diagnostic check to see if it can create the spark needed to light the burner.
Your boiler is struggling to start up because it cannot confirm that the fan is spinning at the right speed to safely clear away exhaust gases.
Your boiler is checking if the pump is moving water correctly but has detected a problem with the flow.
Your boiler has detected a problem with the internal part that switches heat between your radiators and your hot water taps.
Your boiler's electronic control board is failing its internal startup safety checks and cannot safely light the burner.
BoilerFaultCodes