36 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Promax System HE
This boiler uses indicator light combinations
Note which lights are on, off, or flashing and at what speed. Match the combination to the cards below. Do not reset until you have noted the pattern. How to read fault codes →
Tap any card for details
Your boiler is receiving power, but it has been turned off at the main control dial.
Your boiler has detected that it is running too hot or has experienced an internal control error, so it has safely shut itself down to prevent damage.
Your boiler has detected an internal electrical or mechanical fault that is preventing it from circulating water around your home.
Your boiler is struggling because the internal pump, which pushes water around your radiator system, is stuck or has stopped working correctly.
Your boiler is struggling to detect water moving through its system, which prevents it from firing safely.
Your boiler has detected an issue with the airflow system, which means it cannot safely clear waste gases and has therefore shut itself down to prevent a hazard.
Your boiler is failing to light the burner because it cannot detect or create the initial spark, so it has safely shut itself down to prevent a build-up of unburnt gas.
Your boiler is failing to stay lit because it cannot reliably detect the flame needed to heat your home.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has automatically turned itself off because it has become too hot to operate safely.
Your boiler has detected that the internal fan responsible for safely exhausting fumes is not rotating or working correctly, so it has shut down to keep your home safe.
Your boiler has detected an internal error and is refusing to restart even after you have tried to reset it, meaning it cannot operate safely.
Your boiler has switched itself off because it has reached a temperature that is too high, often caused by a circulation problem or a blockage.
Your boiler has got too hot and has automatically shut down to prevent damage.
Your boiler has switched itself off because it has detected that the exhaust gases have become too hot, which is a safety protection measure.
Your boiler has stopped working because it failed to light properly or the waste water pipe is blocked.
Your boiler has shut down because its internal safety sensors detected that it was beginning to overheat.
Your boiler has stopped working because either there isn't enough water pressure in the system or the internal pump is unable to circulate water.
Your boiler has detected a problem with its internal temperature sensors, meaning it cannot accurately measure how hot the water is and has shut down as a safety precaution.
Your boiler has detected that a temperature sensor is not working correctly, which has caused the system to stop running to prevent overheating.
Your boiler is failing to light because it cannot confirm that water is flowing through the system or that the internal fan is operating correctly.
Your boiler has failed to start the fire needed to heat your water and has safely shut itself off to prevent gas from building up.
Your boiler has no electricity flowing to it, meaning it cannot operate or communicate with your heating controls.
Your boiler is currently on and operating normally as part of its internal power check.
Your boiler has stopped working because it cannot light the flame or the internal drainage pipe is backed up with water.
Your boiler has shut itself down because it has detected that the water or the exhaust fumes have become too hot.
Your boiler has detected an issue with how it clears exhaust fumes, preventing it from firing up for safety.
Your boiler has detected that there is not enough water pressure or the water is not moving through the system properly.
Your boiler has lost track of the water temperature and has shut down as a safety precaution.
Your boiler has detected that a temperature sensor is not working correctly, meaning it cannot accurately measure how hot the water is.
Your boiler has stopped working because it cannot clear internal gases to prepare for safe ignition.
Your boiler has lost the water pressure needed to circulate heating around your home, likely due to a minor leak or trapped air.
Your boiler's internal water pressure has climbed too high, which means the system is under too much strain and needs to be brought back down to normal levels.
Your boiler has developed an internal electrical fault that is preventing it from restarting even after you try to reset it.
Your boiler has detected an internal safety issue and has shut itself down to prevent damage, meaning your heating and hot water will not work until it is reset or repaired.
Your boiler has lost its connection to one of its temperature sensors and has shut down to prevent the system from overheating.
BoilerFaultCodes