129 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Promax SL
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 is working normally and has simply reached its target temperature, so it is pausing until the heat is needed again.
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 down as a safety precaution to prevent damage.
Your boiler is struggling to keep its burner lit and is trying to restart itself automatically.
Your boiler is struggling to light its flame after several attempts, which has caused it to shut down for safety.
Your boiler has experienced a brief communication glitch between its internal components and should fix itself automatically.
Your boiler is unable to safely clear exhaust gases, so it has shut down to prevent a fault.
Your boiler is experiencing a temporary communication glitch with its internal computer, but it should fix itself automatically.
Your boiler's computer memory has developed a internal communication error, meaning it can no longer remember how to operate safely.
Your boiler has experienced a brief internal glitch and is currently attempting to restart itself.
Your boiler has encountered a general electrical or internal communication error and has shut down as a safety precaution.
Your boiler has stopped working because the internal fan, which safely exhausts gases, is not spinning or communicating correctly with the system.
Your boiler is not receiving enough electrical power from your home's supply to function correctly.
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
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 brain has developed a terminal fault and can no longer control the heating system safely.
Your boiler is overheating or struggling to move water through the system, causing it to shut down for safety.
Your boiler's internal temperature sensor has stopped working correctly, which prevents the system from knowing when to safely turn the burner on or off.
Your boiler has detected an electrical wiring issue where the power supply wires are connected in the wrong order.
Your boiler's internal computer has developed a fault and can no longer control the heating process safely.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has too much water in the system, which puts unnecessary stress on the internal pipes and seals.
Your boiler has stopped working because there is not enough water pressure in the system to operate safely.
Your boiler has stopped working because there is not enough water pressure in the central heating system.
Your boiler has stopped working because the water isn't moving through the system properly, causing it to overheat and shut down for safety.
Your boiler has failed to heat your water tank to a high enough temperature to safely kill off any potential bacteria.
Your boiler started to heat up but the flame went out unexpectedly before finishing the job.
Your boiler has tried to light several times but has been unable to successfully create or detect a flame.
Your boiler has experienced an internal communication error, typically caused by someone pressing the reset button for too long or a fault with the main electronic control board.
Your boiler has detected that the internal fan, which safely exhausts gases, is not spinning at the correct speed or has stopped working entirely.
Your boiler has stopped working because it cannot confirm that the fan is clearing away waste gases safely.
Your boiler has stopped working because it cannot detect the correct flow of water through the system.
Your boiler has detected an issue with how air is moving through the system, preventing it from lighting safely.
Your boiler has detected that it is heating up without enough water inside it, causing it to overheat rapidly to protect the internal parts.
Your boiler has detected an electrical safety grounding issue, which means it cannot fire up safely until the connection is restored.
Your boiler has shut down because it has become dangerously hot and is protecting itself from overheating.
Your boiler has lost connection with a internal temperature sensor and has stopped working as a safety precaution.
Your boiler has lost communication with the temperature sensor that monitors water returning to the unit, preventing it from heating your home safely.
Your boiler has detected that the water temperature readings are the wrong way around, which usually means the water isn't flowing through the system correctly.
Your boiler is repeatedly failing to keep the flame lit, causing the system to lock itself out for safety.
Your boiler's fan unit is struggling to move air correctly, which could be caused by strong winds outside or a mechanical failure within the system.
Your boiler has stopped working because it believes the water coming back from your radiators is hotter than the water leaving the unit, which is usually caused by a circulation problem or a sensor error.
Your boiler has stopped working because it cannot move water through the system properly or a internal sensor has lost its connection.
Your boiler has shut down because it is getting too hot inside, likely because water isn't moving through the system properly.
Your boiler is simply acknowledging that the reset button has been pressed and is now attempting to restart its normal operation.
Your boiler has stopped working because the water pressure in the system has dropped too low to operate safely.
Your boiler’s internal computer has suffered a serious electronic failure and can no longer control the heating process safely.
Your boiler has lost the internal connection between its main control board and the gas system, meaning it cannot safely fire up to provide heat.
Your boiler’s internal control board has detected an incorrect configuration setting, which is preventing it from starting up properly.
Your boiler’s internal control board has detected an incorrect configuration setting, likely due to a technical adjustment or a component fault.
Your boiler's main control board has detected a configuration setting error, likely caused by a hardware connection issue inside the unit.
Your boiler is having trouble communicating with an external control, such as your thermostat or programmer, due to a connection or wiring fault.
Your boiler is having trouble communicating with your thermostat or external programmer, meaning it doesn't know when to turn on or off.
Your boiler has stopped working because it cannot communicate with the component that controls the gas supply.
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 stopped working because it cannot accurately measure the temperature of the water flowing through the system.
Your boiler has overheated because water isn't moving through the system properly, causing it to shut down for safety.
Your boiler has detected an issue with the sensor that monitors exhaust gases, causing it to shut down for safety.
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 likely overheated because heat is not moving away from the unit or a safety sensor has detected a temperature that is dangerously high.
Your boiler has switched itself off because it has detected it is getting too hot, likely due to water not moving through the system properly.
Your boiler is trying to start up but cannot ignite the gas flame, meaning your heating and hot water will not work.
Your boiler thinks a flame is burning when it shouldn't be, or it is struggling to manage the gas and air mixture correctly, causing it to shut down for safety.
Your boiler has stopped working because the fan that clears away waste gases is jammed or cannot spin properly.
Your boiler has detected a serious internal communication or hardware failure within its gas control system, preventing it from firing up safely.
Your boiler has stopped working because it cannot accurately measure the temperature of the water inside the system.
Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
Your boiler is overheating because water isn't moving through the system properly, often because of trapped air.
Your boiler's internal computer has developed a fault and can no longer control the heating process safely.
Your boiler has failed to light, likely because air is trapped in the system or there is an issue with the fuel supply.
Your boiler has lost communication with the gas valve, meaning it cannot safely ignite to provide heating or hot water.
Your boiler is struggling to understand the temperature outside, which is preventing it from managing your heating efficiently.
Your boiler has stopped working because water is not flowing through the system correctly to prevent overheating.
Your boiler has detected that a water flow sensor is stuck in the 'on' position, preventing the system from starting its safety checks properly.
Your boiler's electronic controller is unable to communicate properly with the gas valve, meaning the system cannot safely light the flame.
Your boiler has lost its connection to the sensor that monitors the temperature of the water circulating through your radiators.
Your boiler has detected a problem with how it safely gets rid of waste gases or moisture through the exhaust pipe, causing it to shut down for safety.
Your boiler has detected an issue with the sensor that monitors the water temperature coming back from your radiators, preventing it from heating your home safely.
Your boiler has lost its connection to the sensor that monitors the temperature of your hot water, preventing it from heating correctly.
Your boiler is not getting enough air to burn gas safely, which could be caused by an obstruction in the external vent or a component failure.
Your boiler is having trouble detecting when you turn on the hot water tap, meaning you will likely have no hot water or inconsistent temperatures.
Your boiler’s internal computer has lost track of its settings and needs to be professionally reconfigured to ensure it burns gas efficiently.
Your boiler has lost the ability to monitor its own water pressure, meaning it has shut down to prevent potential damage.
Your boiler's main control board has lost connection with its internal display or external smart controls, preventing it from receiving instructions to turn on.
Your boiler has failed an internal safety check while trying to automatically adjust its burner settings.
Your boiler’s internal computer chip has lost track of time or suffered a memory error, preventing it from managing your heating correctly.
Your boiler is struggling to move water through the system properly, which is causing it to stop to prevent overheating.
Your boiler has shut down because it has detected an unsafe increase in temperature, likely due to a circulation problem or overheating.
Your boiler has detected that there is too much water pressure in the system, which has caused it to stop working for safety.
Your boiler has stopped working because the water pressure in your heating system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure in the heating system is too low.
Your boiler is struggling to move heated water through the pipes, which usually means the pump has failed or there is a blockage in the system.
Your boiler is repeatedly losing its flame mid-operation and has locked itself out for safety after trying to restart too many times.
Your boiler is struggling to keep its flame lit during its initial checks and cannot fuel itself correctly to stay running.
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 it has detected that the exhaust gases are becoming too hot, which is a safety feature to prevent damage to the system.
Your boiler has failed to light because it isn't getting enough gas or it cannot detect a flame once it has started.
Your boiler is failing to light the burner because it hasn't detected a flame within the allowed time.
Your boiler has stopped working because it cannot detect a steady flow of gas or it has lost its flame during operation.
Your boiler has detected that the water temperature readings are inconsistent, which usually means the water isn't flowing correctly through the system.
Your boiler has detected a problem with the fan that clears out exhaust gases, which has caused the system to shut down for safety.
Your boiler's fan, which safely clears waste gases away, has stopped spinning correctly, meaning the boiler has shut down for safety.
Your boiler has lost its connection to the sensor that monitors your hot water temperature, meaning it can't safely heat the water for your taps.
Your boiler has lost the ability to monitor its own water pressure, which prevents it from operating safely to heat your home.
Your boiler's internal computer has developed a fault and is struggling to communicate with the rest of the unit.
Your boiler's internal computer brain is struggling to process instructions or has detected an internal electrical fault, causing the system to shut down for safety.
Your boiler has detected that water is not moving through the system correctly before the burner starts up.
Your boiler has detected that water isn't moving through the system properly, which is causing it to overheat quickly.
Your boiler has detected that the electricity supply coming into your home is at the wrong frequency, which usually indicates an issue with the power grid or a faulty internal circuit board.
Your boiler is struggling to accurately measure the temperature of your hot water due to a faulty sensor.
Your boiler thinks there is a flame burning when there shouldn't be, which is a safety conflict that prevents it from starting up.
Your boiler is not receiving enough electrical power to operate safely, which is usually caused by an internal circuit board failure or an issue with your home's power supply.
Your boiler is checking if there is enough water pressure to run safely and has paused briefly to confirm the system is full.
Your boiler has lost its connection to the gas control system, preventing it from lighting safely.
Your boiler is shutting down because the water inside it is heating up too quickly or isn't moving around your radiators properly.
Your boiler is overheating because water isn't moving through the system quickly enough or a sensor is misreading the temperature.
Your boiler has shut down because it is getting too hot too quickly, likely due to water not flowing through the system's pipes properly.
Your boiler has likely stopped heating because water is not flowing through the system correctly or a temperature sensor has developed a fault.
Your boiler is heating up too quickly because water isn't moving through the system fast enough to carry the heat away.
Your boiler’s internal computer chip has lost its settings and doesn't know how to operate the system.
Your boiler's computer memory has become confused about its internal settings, causing it to stop running temporarily.
Your boiler's internal computer has become confused by its own settings and is struggling to communicate with its electronic brain.
Your boiler has detected that the water pressure is either too low or there is a leak somewhere in the heating system, causing it to stop Working as a safety precaution.
Your boiler is having trouble 'talking' to its internal temperature sensors, which is preventing it from heating up correctly.
Your boiler's internal computer is having trouble talking to its other components, meaning it cannot start the heating process.
Your boiler has lost its flame while it was running, which means it cannot heat your water or radiators.
Your boiler appears to have no electrical power at all, meaning the display is blank and the unit cannot start up.
Your boiler has failed to light the gas flame after several attempts and has shut itself down for safety.
Your boiler has detected an internal electrical communication problem between its main control components, meaning it cannot start up to provide heat.
BoilerFaultCodes