151 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Greenstar 28i Junior
This boiler uses LED flash patterns
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Your boiler has detected a communication error between its electrical components or an issue with the air fan, causing it to shut down for safety.
Your boiler has been left in a manual testing mode, usually used by engineers during a service, which is preventing it from running normally.
Your boiler has been left in a manual testing mode after a recent service and needs to be switched back to its normal operating setting.
Your boiler’s internal computer components are not talking to each other properly, likely due to a software mismatch or an incorrect spare part being installed.
Your boiler’s internal computer chip is giving an error message because it thinks it has been fitted with the wrong component or cannot communicate with it.
Your boiler's computer memory chip is not communicating correctly with the main control board, preventing the system from starting up.
Your boiler is working correctly and is simply indicating that it is currently busy heating your radiators.
Your boiler is working correctly and is simply letting you know that it is currently busy heating up your radiators.
Your boiler is simply indicating that it is currently heating your hot water and is working as expected rather than having an actual fault.
Your boiler is simply notifying you that it is currently busy heating up water for your taps or shower.
Your boiler is working normally and is simply waiting for a signal from your thermostat or timer to start heating.
Your boiler is temporarily resting to prevent it from turning on and off too frequently, which helps protect its internal parts from unnecessary wear.
Your boiler is currently in standby mode and is working correctly, simply waiting for you to turn on your heating or hot water.
Your boiler is working correctly but is currently resting because your thermostat or timer is not telling it to come on.
Your boiler is currently taking a temporary rest because it has reached its target temperature and is waiting for the water inside to cool down slightly before firing up again.
Your boiler is currently hotter than it is supposed to be, so it has temporarily stopped firing to allow the water inside to cool down.
Your boiler has been manually set to a testing mode used by engineers to check emissions and is not currently operating in its normal heating mode.
Your boiler is currently set to a manual testing mode used by engineers to check emissions, and it won't operate normally until this is switched off.
Your boiler is overheating because the water inside it is getting too hot much faster than it should.
Your boiler has switched itself off because the water pressure is too low for it to operate safely.
Your boiler has recorded that a technician's diagnostic tool was plugged into the system's memory menu, but it is not a mechanical fault with the boiler itself.
Your boiler is trying to light but cannot detect a flame, which means it has stopped working to keep you safe.
Your boiler thinks it sees a flame even though it isn't actually firing, which is preventing it from starting up safely for heating or hot water.
Your boiler’s internal computer and main control parts are unable to talk to each other because their software versions do not match.
Your boiler has started up, but it cannot detect the water getting any warmer, so it has shut down to prevent overheating.
Your boiler is temporarily limiting its power output because it is producing more heat than your radiators or taps can currently take away.
Your boiler is currently running a self-diagnostic check of its internal parts, which it usually does automatically after a reset or power cut.
Your boiler is not broken; it is simply increasing its power level to meet the heat demand for your radiators or hot water.
Your boiler is currently going through its normal startup sequence and is getting ready to light the burner.
Your boiler has detected a signal error from the gas valve, causing it to shut down for safety.
Your boiler is temporarily paused while it finishes a period of providing hot water, but it has not yet switched back to heating mode.
Your boiler is temporarily pausing the hot water production to prevent itself from overheating or cycling too frequently.
Your boiler is still detecting a flame even after it has been told to shut off the gas, which usually means a internal valve is stuck or leaking.
Your boiler is struggling with an unstable electrical supply or an internal computer error, causing it to shut down for safety.
Your boiler is not receiving a stable or strong enough supply of electricity to operate safely.
Your boiler's internal computer chips are not communicating correctly or don't match, preventing the system from starting up for safety.
Your boiler is displaying an error because it doesn't recognize the internal data chip that tells it how to operate correctly.
Your boiler's internal temperature sensors are giving conflicting or incorrect readings, causing the system to stop working to prevent damage.
Your boiler has lost its internal connection to the smart controls or sensors, meaning the communication brain cannot talk to the heating components.
Your boiler has stopped working because the water pressure is too low for it to run safely.
Your boiler is unable to measure the temperature of the water coming out of your taps, which usually means your hot water will be cold or inconsistent.
Your boiler is struggling to monitor the temperature of your hot water, which usually means it cannot heat it safely or effectively.
Your boiler is struggling to understand how cold it is outside because a weather sensor has failed or become disconnected.
Your boiler cannot accurately measure the water pressure inside the system, which has caused it to stop working for safety reasons.
Your boiler's external temperature sensor is sending an incorrect signal or is no longer communicating, which may affect how efficiently your heating responds to the weather.
Your boiler has detected an electrical fault with its internal thermometer, meaning it can't safely monitor water temperature and has stopped working as a precaution.
Your boiler has lost connection with a key internal sensor that monitors how hot the water is, preventing it from heating up properly.
Your boiler has detected an electrical fault with its internal temperature sensor, preventing it from heating your water safely.
Your boiler has stopped working because it cannot communicate with the internal sensor that monitors the temperature of the main heating unit.
Your boiler has stopped working because it cannot detect a flame or has lost the flame signal during operation.
Your boiler has stopped working because the internal control panel cannot communicate with the part that regulates the gas flow.
Your boiler has stopped working because the internal control board cannot communicate correctly with the gas valve that manages the flame.
Your boiler has unexpectedly lost its flame while running and can no longer stay lit to provide heating or hot water.
Your boiler's internal computer chip is failing to communicate correctly, meaning the system doesn't know which model it is and has stopped working for safety.
Your boiler is struggling to detect a flame when it tries to start, meaning it cannot safely stay on to provide heat or hot water.
Your boiler is struggling to detect or maintain a flame, meaning it keeps stopping and trying to restart itself to provide heat and hot water.
Your boiler has detected that its internal temperature sensors are sending an unusual signal, likely due to a loose connection or a faulty sensor.
Your boiler is struggling to push water through the heating system, likely due to a blockage, air pocket, or a failing pump.
Your boiler has sensed that the water inside is getting much hotter than it should be and has shut down as a safety precaution.
Your boiler has detected that the water inside is heating up too quickly, which usually means the water isn't flowing through the system as it should.
Your boiler has sensed a sudden, unusual temperature difference between two internal parts and has shut down to prevent overheating.
Your boiler has lost water pressure very suddenly, which has caused it to stop working to protect the internal components.
Your boiler has detected that the water pressure is too low, or the sensor that monitors the pressure is faulty, causing the system to stop working.
Your boiler has detected that it is running without enough water inside, which is often caused by a leak or a pump that has jammed or failed.
Your boiler's internal pump is either jammed or struggling to move water because there is air trapped inside the unit.
Your boiler has detected an electrical fault with the sensor that monitors the safety of exhaust gases, causing the system to shut down for protection.
Your boiler's hot water sensor is not reading the temperature correctly, which usually means your hot water will be cold or the temperature will fluctuate significantly.
Your boiler has lost its connection to your external room thermostat or heating controls, meaning it doesn't know when to turn on or off.
Your boiler is not receiving the steady supply of electricity it needs to run, which is usually caused by an internal circuit board fault or a problem with the local power supply.
Your boiler's internal computer brain cannot find its identity chip, which prevents the system from starting up.
Your boiler's internal computer has encountered a critical electronic failure and can no longer communicate with the rest of the system.
Your boiler has detected that the internal fan or air supply has stopped working while it was running, causing it to shut down for safety.
Your boiler's main internal computer has developed a serious electronic fault and can no longer control the heating process safely.
Your boiler's fan system is reporting an internal airflow error that suggests a technical component failure or a blockage in the flue.
Your boiler has detected that its internal fan is not spinning fast enough to safely clear away exhaust fumes, which has caused the system to shut down for safety.
Your boiler has identified a technical internal fault with the fan and has shut down as a safety precaution to ensure exhaust gases are cleared correctly.
Your boiler has stopped working because the internal fan that clears out exhaust fumes is not spinning fast enough to operate safely.
Your boiler's fan has failed to start, which means the system cannot safely clear exhaust gases and has shut down as a safety precaution.
Your boiler has stopped working because the internal fan, which safely clears away exhaust gases, is not spinning at the correct speed.
Your boiler has shut down because the internal fan, which safely exhausts waste gases, has stopped working while the boiler was running.
Your boiler is unable to communicate with its outdoor temperature sensor, meaning it cannot adjust its heating efficiency based on the weather outside.
Your boiler has stopped working because there is not enough water in the system to operate safely.
Your boiler has failed its internal safety check because it cannot detect water moving through the system properly.
Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has developed a fault or become wet.
Your boiler has stopped working because it has lost its connection to the internal sensor that monitors the water returning from your radiators.
An external safety device or heating control has disconnected, telling the boiler to stop running for protection.
Your boiler is shutting down because it is heating up too fast, which usually means the water isn't circulating properly through the system.
Your boiler has detected that water is getting too hot too quickly or is not moving through the system properly, causing it to shut down for safety.
Your boiler has shut down because it is overheating, meaning the water returning to the unit is significantly hotter than it should be.
Your boiler is heating up much quicker than it should and is shutting down to prevent overheating, likely because the water isn't moving through the system properly.
Your boiler's internal thermometer that measures the temperature of the water heading to your radiators has developed a fault and can no longer read the temperature correctly.
Your boiler has detected an electrical fault with the internal sensor that monitors water temperature, 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 lost communication with the internal thermometer that monitors water temperature, causing the system to shut down for safety.
Your boiler has detected a fault with the sensor that monitors the water temperature leaving the unit, usually caused by a faulty component or damaged wiring.
Your boiler has stopped working because it can no longer track the temperature of the water leaving the unit, leading to a complete shutdown of heating and hot water.
Your boiler has stopped working because the water inside has become far too hot, causing the system to shut down for safety.
Your boiler has switched itself off because it has detected that the water inside is getting too hot, likely due to a circulation problem or low pressure.
Your boiler has shut down because it is detecting dangerously high temperatures inside the exhaust flue.
Your boiler has detected that it is getting too hot and has shut down as a safety precaution to prevent damage.
Your boiler has shut down because it has detected an unsafe level of overheating or a faulty internal sensor.
Your boiler has switched itself off because internal sensors have detected that the water or exhaust gases have become dangerously hot.
Your boiler has shut down because the water inside it has become dangerously hot and reached a level that risks damaging the internal components.
Your boiler has reached an unsafe temperature and shut itself down to prevent overheating and internal damage.
Your boiler has reached an unsafe temperature and has shut down as a safety precaution to prevent internal damage.
Your boiler has shut down because a safety sensor has detected that the exhaust gases are getting too hot or the sensor itself has a faulty connection.
Your boiler has stopped working because it cannot light the flame, which is usually caused by a temporary interruption in the gas supply or a part that needs cleaning.
Your boiler has tried to light but cannot detect a flame, or the flame is going out shortly after starting, which has caused the system to stop working for safety.
Your boiler has lost its flame while it was running, which means it has safely shut down to prevent unburnt gas from escaping.
Your boiler has lost its connection to the gas valve, meaning it cannot light the flame to provide heating or hot water.
Your boiler's main control computer is experiencing a software glitch or internal failure, causing the system to lock out for safety.
Your boiler is trying to start up but cannot successfully light the gas flame, causing it to shut down for safety.
Your boiler's internal computer has encountered a critical error and has stopped the burner from firing to keep the system safe.
Your boiler is struggling to move water around the system properly, causing it to throttle its power back to prevent overheating.
Your boiler’s internal computer has developed a serious communication fault and can no longer control the heating process safely.
Your boiler has experienced an internal electrical communication error, meaning it cannot process the signals needed to stay running safely.
Your boiler has experienced a serious internal electronic failure, meaning the main control board can no longer communicate with the boiler's components.
Your boiler has detected an internal electrical fault with the gas control system, meaning it cannot safely ignite to provide heating or hot water.
Your boiler's electronic brain has developed a fault and can no longer control the heating and hot water safely.
Your boiler's internal computer has encountered a major electronic communication fault, meaning it cannot process the commands needed to heat your home.
Your boiler's internal computer has encountered a critical communication error and can no longer control the heating process safely.
Your boiler's internal computer has encountered a critical communication error and can no longer control the heating process safely.
Your boiler’s internal computer has developed a serious fault, meaning it can no longer safely control the heating and hot water process.
Your boiler's internal computer has detected a communication issue with its sensors, meaning it cannot accurately check if the system is running safely.
Your boiler's internal computer has developed an electrical fault and can no longer safely control the flame, meaning the system has shut itself down.
Your boiler's main internal computer has developed a communication fault or an electronic failure, meaning the unit cannot safely manage the heating process.
Your boiler's internal computer has developed a communication fault and cannot safely ignite the burner.
Your boiler's internal computer has encountered a critical error and can no longer communicate with the main controls, meaning the unit will not fire up.
Your boiler's computer has developed a fault and can no longer communicate with the internal components, meaning the system cannot run.
Your boiler’s internal computer has developed a fault and can no longer control the heating and hot water process safely.
Your boiler thinks it sees a flame even though it should be turned off, which is a safety conflict that prevents the system from starting.
Your boiler thinks it sees a flame even though it hasn't actually started the burners yet, causing it to stop for safety.
Your boiler has experienced a brief momentary interruption in power and needs to be restarted.
Your boiler is still detecting a flame even though it has tried to shut the gas off, which is a safety concern that requires professional attention.
Your boiler is still detecting a flame even though it has tried to turn itself off, which is a safety conflict that stops the unit from running.
Your boiler has detected a potential internal gas leak or a hardware failure within the gas valve assembly, causing it to shut down for safety.
Your boiler has detected a potential internal gas leak within its own control system and has shut down for safety.
Your boiler has entered a temporary lock-out state because the reset button was held down for too long or pressed by accident.
Your boiler has detected an unexpected interruption or irregularity in its electrical power supply, which has caused it to stop working for safety.
Your boiler has detected that the water pressure is too low, which is preventing it from heating your radiators or providing hot water effectively.
Your boiler is experiencing an internal computer error that is causing it to restart repeatedly, preventing it from heating your home properly.
Your boiler is standing by and waiting for a signal to start, which usually means your thermostat is turned down or your timer hasn't told it to switch on yet.
Your boiler is operating normally and is currently providing heat to your radiators.
Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.
Your boiler has lost power completely, meaning it will not turn on or provide any heating or hot water until the electrical supply is restored.
Your boiler is undergoing a restart process, which is often a temporary reaction to a minor internal fault or a manual reset action.
Your boiler is currently testing its ability to create a spark to light the burner.
Your boiler's fan system is failing its initial safety check, which prevents the boiler from starting up to provide heating or hot water.
Your boiler is checking if the internal pump is moving water correctly and has detected it might be stuck or failing.
Your boiler has failed an internal test of the component that switches water between your radiators and your taps, meaning your heating or hot water may not work correctly.
Your boiler has detected an internal electrical problem during its ignition safety check, which prevents it from firing up safely.
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