129 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Potterton Promax 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 its set temperature and is temporarily resting; it is working exactly as it should.
Your boiler has detected that it is getting too hot or that water isn't moving through the system correctly, causing it to shut down for safety.
Your boiler has become too hot and has automatically shut itself down to prevent damage.
Your boiler is struggling to keep its flame lit and is currently trying to fix the problem automatically.
Your boiler has tried to light several times but cannot establish a flame, leaving you without heating and hot water.
Your boiler is having a temporary 'conversation' issue between its internal parts and should fix itself momentarily without you needing to do anything.
Your boiler's internal cooling and exhaust fan is not spinning or communicating correctly, preventing the system from starting up for safety.
Your boiler has experienced a temporary electronic glitch in its control system, but it is programmed to fix itself and restart automatically.
Your boiler's internal memory or brain is experiencing a technical failure, meaning it can no longer remember how to operate correctly.
Your boiler has encountered a minor temporary glitch and is currently trying to restart itself automatically.
Your boiler has encountered a general electrical or internal system error that is preventing it from running properly.
Your boiler has stopped working because the internal fan, which safely exhausts waste gases, is not spinning or starting correctly.
Your boiler is not receiving enough electrical power from your home's supply to operate safely and has shut down as a precaution.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler's electronic control centre has developed an internal fault and is no longer able to manage the heating process safely.
Your boiler’s main control board has developed an internal electrical fault and can no longer send signals to heat your home.
Your boiler has detected that water is not moving through the system properly or there is not enough water inside, causing it to overheat quickly.
Your boiler has detected a problem with its temperature sensor, which means it cannot tell if the water is getting too hot and has shut down as a safety precaution.
Your boiler has detected an issue with the electrical power connection, meaning the wiring likely doesn't match the safety standards required to operate.
Your boiler's internal control board has developed an electrical fault and is unable to manage the heating process safely.
Your boiler has become too hot and has shut down as a safety measure to prevent damage.
Your boiler has too much water in the system, which puts extra strain on the internal seals and safety components.
Your boiler has detected that there is not enough water in the system to operate safely, causing it to shut down to prevent damage.
Your boiler has stopped working because there is not enough water pressure in the system to operate safely.
Your boiler has detected that water is not moving through the system properly, which is causing it to overheat and shut down for safety.
Your boiler has failed to heat your hot water tank to a high enough temperature to kill off potentially harmful bacteria.
Your boiler started up correctly but the flame went out unexpectedly while it was running, causing the system to shut down for safety.
Your boiler is trying to light, but the burner isn't staying on or starting up as it should.
Your boiler has likely experienced a communication failure between its components or has been reset too many times in a short period.
Your boiler has stopped working because the internal fan, which safely exhausts gases, is not spinning or communicating correctly with the system.
Your boiler has stopped working because it cannot confirm that the fan is safely exhausting waste gases away from your home.
Your boiler has detected that water is not circulating correctly through the system, causing the heater to stop working for safety.
Your boiler has stopped working because it cannot confirm that the fan is safely clearing waste gases from the system.
Your boiler has detected that it is trying to heat up without enough water flowing through it, which could cause it to overheat.
Your boiler has detected a problem with its electrical grounding, which could mean a loose wire or a fault in the main control board.
Your boiler has shut down because it has detected that the water inside is getting much hotter than it safely should.
Your boiler has detected that a sensor used to monitor the temperature of the water returning to the unit is either disconnected or faulty, causing the system to stop working as a safety precaution.
Your boiler has stopped working because it cannot correctly detect the temperature of the water returning to the unit, likely due to a faulty internal sensor or a loose wire.
Your boiler is confused because it thinks the water returning from your radiators is hotter than the water it just sent out, which usually means there is a circulation problem or a sensor fault.
Your boiler is repeatedly losing its flame and failing to stay lit, which has caused it to lock out for safety.
Your boiler's fan is not spinning at the correct speed to safely clear exhaust fumes, often caused by a mechanical failure or a strong gust of wind blocking the flue.
Your boiler has sensed that the water returning to it is hotter than the water leaving it, which usually means there is a blockage or the sensors are confused.
Your boiler has likely stopped working because it is unable to move water around the system or it has lost contact with its internal temperature sensors.
Your boiler has shut down because it is getting too hot inside, likely due to water not moving through the system properly.
Your boiler is simply acknowledging that the reset button was held down or pressed, which can sometimes happen during a restart or by mistake.
Your boiler has detected that there is not enough water in the heating system to operate safely, causing it to shut down.
Your boiler’s internal computer has suffered a critical failure or a communication timeout and can no longer control the heating process.
Your boiler's computer is unable to talk to the part that controls the gas supply, preventng the system from heating your home.
Your boiler's main control board has detected an internal configuration error that is preventing it from running correctly.
Your boiler's main control board has detected a configuration setting error, likely caused by a component failure or an accidental change during a recent repair.
Your boiler's internal computer settings have been altered or are incorrect, preventing it from starting up properly.
Your boiler is having trouble communicating with external parts like your thermostat or pump due to a wiring issue.
Your boiler is having trouble communicating with your thermostat or external programmer, meaning it cannot receive the signal to turn your heating on.
Your boiler's internal computer has lost communication with the gas valve, meaning it 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.
Your boiler has lost its connection to the sensor that measures how hot the water is getting, causing the system to shut down for safety.
Your boiler has reached a dangerously high temperature because water is not moving through the system properly.
Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.
Your boiler has detected an issue with the sensor that monitors exhaust gases, causing the system to shut down for safety.
Your boiler has shut down because it is getting too hot, likely due to water not moving through the system properly or a faulty safety sensor.
Your boiler has overheated or detected a serious circulation issue, causing it to shut down for safety.
Your boiler is struggling to ignite a flame, meaning your heating and hot water will not work until it is reset or repaired.
Your boiler thinks a flame is burning when it shouldn't be, causing the system to lock out for safety.
Your boiler has detected that the internal fan, which safely clears exhaust gases out of the flue, has stopped spinning or is broken.
Your boiler has detected a serious internal communication or hardware failure within the gas management system and has locked itself out for safety.
Your boiler's internal thermometer has stopped working correctly, so the system has shut down because it can no longer monitor how hot the water is getting.
Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
Your boiler is struggling to push water around the system, often because trapped air is acting like a blockage.
Your boiler's internal computer has developed a fault and is unable to control the heating process safely.
Your boiler has failed to light the flame, which means you will not have any heating or hot water until it is reset or repaired.
Your boiler has lost its electrical connection to the gas supply valve, meaning it cannot ignite to provide heat or hot water.
Your boiler is having trouble communicating with the temperature sensor located outside your home, which helps it decide how hard to work based on the weather.
Your boiler has detected that water isn't moving through the system correctly, which has caused it to shut down to prevent overheating.
Your boiler has detected that a water flow sensor is stuck in the 'on' position even when the pump is off, preventing the system from starting safely.
Your boiler has lost the ability to control the flow of gas correctly and has shut down as a safety precaution.
Your boiler has lost its ability to measure the temperature of the water used for heating, which is preventing it from running safely.
Your boiler has detected a problem with how it disposes of exhaust gases or a sensor failure, causing it to shut down for safety.
Your boiler has detected an issue with the sensor that reads the temperature of the water returning to the unit, causing the heating to shut down for safety.
Your boiler has lost its connection to the sensor that monitors hot water temperature, meaning it cannot safely heat your water to the correct level.
Your boiler is not getting enough air to burn gas safely, which is likely caused by an obstruction in the external vent pipe.
Your boiler is struggling to detect when you turn on your hot taps, which may prevent the water from heating up correctly.
Your boiler's internal computer has lost its settings and can no longer correctly manage the balance of gas and air for the burner.
Your boiler has detected an issue with the sensor that monitors internal water pressure, meaning it cannot confirm if there is enough water to run safely.
Your boiler's internal computer brain is struggling to talk to its sensors or controls, meaning it cannot process the instructions needed to heat your home.
Your boiler has failed an internal safety check while trying to automatically adjust its burner settings.
Your boiler's main control board has lost track of the time or date, which prevents it from running its scheduled heating programmes correctly.
Your boiler is overheating because water is not moving through the system quickly enough to carry the heat away.
Your boiler has overheated, causing a safety switch to trip and shut down the system to prevent damage.
Your boiler has detected that there is too much water pressure in the system, which causes it to shut down for safety.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure is too low for the system to run safely.
Your boiler has stopped working because water is not moving around the pipes properly, causing it to overheat and shut down for safety.
Your boiler has lost its flame multiple times in a row and has locked itself out for safety.
Your boiler is struggling to keep its internal flame lit and has reached its limit of automatic self-corrections while trying to start up.
Your boiler has shut down because a sensor has detected that the exhaust gases are becoming too hot.
Your boiler has shut down because it detected that the exhaust gases have become too hot, which is a safety feature to prevent damage or dangerous fumes.
Your boiler is failing to light the flame, which is often caused by a lack of gas reaching the unit or a temporary ignition glitch.
Your boiler has tried to ignite several times but cannot detect a flame, likely because gas is not reaching the burner or the ignition system is failing.
Your boiler has lost its fuel connection or cannot detect the gas supply needed to light the flame.
Your boiler has detected that the water is heating up too quickly or there is an unusual difference in temperature between the pipes, causing it to shut down for safety.
Your boiler has stopped working because the fan that safely clears away exhaust gases is not spinning or communicating with the control board.
Your boiler has detected a problem with the fan that clears away waste gases, causing the system to shut down for safety.
Your boiler has lost its connection to the sensor that monitors hot water temperature, meaning it can no longer safely heat your tap water.
Your boiler is having trouble monitoring its internal water pressure, which has caused it to stop running for safety.
Your boiler's internal computer has developed a fault and is struggling to communicate with the rest of the system.
Your boiler's internal computer has crashed and can no longer process data or communicate with the system components.
Your boiler is struggling to move water around the system properly before it starts the heating process, often due to a blockage or a pump issue.
Your boiler is overheating because water isn't moving through the system properly, causing it to shut down to prevent damage.
Your boiler has detected an issue with the electrical power timing coming into the unit, which is preventing it from running safely.
Your boiler's hot water sensor has failed or is sending an incorrect reading, meaning the system cannot heat your water safely or accurately.
Your boiler thinks it sees a flame even though it hasn't finished its startup checks, so it has shut down for safety.
Your boiler is not receiving enough electrical power to run safely and has shut down to protect its internal components.
Your boiler is temporarily checking if there is enough water pressure in the system to operate safely.
Your boiler has lost its connection to the gas control system, preventing it from lighting safely.
Your boiler is overheating because water isn't moving through the system quickly enough or a sensor is giving a false reading.
Your boiler is overheating or water isn't moving through the system fast enough to keep it cool.
Your boiler has detected that the water is getting too hot too quickly, likely because it cannot flow through the system properly.
Your boiler has stopped working because water is not moving through the system properly or a sensor is detecting an incorrect temperature.
Your boiler is heating up too quickly because water isn't moving through the system properly or a sensor is misreading the temperature.
Your boiler's internal computer brain hasn't been programmed with the specific settings it needs to run properly.
Your boiler's control system is temporarily confused by its own internal configuration settings.
Your boiler's internal computer has become confused by its own settings, causing it to stop running temporarily.
Your boiler has detected low water pressure, which means there isn't enough water inside the pipes to keep the system running safely.
Your boiler has stopped working because its internal computer has lost contact with one of the temperature sensors.
Your boiler's internal computer is having trouble talking to its other components, causing the system to shut down for safety.
Your boiler has lost its flame while it was running and has safely shut down to prevent issues.
Your boiler has no electricity reaching it and the display has completely shut down.
Your boiler has tried to start up but failed to light the flame, causing the system to shut down for safety.
Your boiler has detected an internal electrical communication problem and has shut down as a safety precaution.
BoilerFaultCodes