27 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: ecoTEC plus
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 has stopped working because it failed to light the flame properly, so it has safely shut itself down to prevent gas from building up.
Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit due to a sensor or wiring fault.
Your boiler has stopped working because one of its internal temperature sensors is unable to send a signal to the main control board.
Your boiler has detected an electrical fault with the internal temperature sensor that monitors the outward flow of water, causing the system to shut down for safety.
Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has detected a short circuit.
Your boiler has switched itself off because it has become too hot internally, usually due to a lack of water flow or a blockage.
Your boiler has detected that there is not enough water pressure or flow to operate safely and has shut down to prevent overheating.
Your boiler has detected that the water isn't moving through the system correctly, causing it to heat up too quickly and shut down for safety.
Your boiler is heating up too quickly because water isn't moving through the system properly, causing it to shut down to prevent overheating.
Your boiler has detected a flame when there shouldn't be one, which has caused it to shut down for safety.
Your boiler is failing to light because it isn't receiving gas or the ignition system isn't creating a spark.
Your boiler has lost its flame while running and cannot restart, likely because it is not getting enough gas or the ignition system is failing.
Your boiler has stopped working because the internal fan isn't spinning at the correct speed to safely clear away exhaust fumes.
Your boiler has stopped working because it cannot confirm that harmful exhaust fumes are being safely cleared away through the flue pipe.
Your boiler has stopped working because the fan that clears exhaust gases is not spinning at the correct speed or the sensor that monitors it has failed.
Your boiler has lost its memory regarding the type of gas it uses and needs to be reconfigured by a professional to operate safely.
Your boiler has stopped working because of a wiring issue or an electrical connection problem inside the main control panel.
Your boiler has detected an internal wiring problem or a connection issue that is preventing it from running safely.
Your boiler's internal computer has encountered a critical electronic failure and can no longer control the heating process safely.
Your boiler's internal computer has encountered a communication error or a serious hardware failure that prevents it from running safely.
Your boiler is still detecting a flame even after it has told the gas to turn off, which is a safety conflict that causes the system to shut down.
Your boiler has detected an internal electrical communication error, which means the main control board is likely faulty and cannot manage the heating process safely.
Your boiler has detected an internal electrical glitch or a faulty temperature sensor, causing it to shut down for safety.
Your boiler's internal computer has overheated, likely due to an electrical fault or a failing circuit board.
Your boiler's main control panel is having trouble communicating with the internal display screen, meaning you cannot see or adjust your heating settings.
Your boiler's internal computer has encountered a communication error or hardware failure and cannot operate safely.
Your boiler has stopped working because the water pressure is too low for it to run safely.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes