18 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: CDX
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 →
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Your boiler's internal thermometer is malfunctioning, meaning the system can no longer tell how hot the water is and has stopped working to keep you safe.
Your boiler has automatically turned itself off because it became too hot, often due to a restriction in the water flow.
Your boiler has lost track of how hot it is inside, so it has safely shut itself down to prevent overheating.
Your boiler has detected that it is getting too hot and has automatically shut down to prevent damage.
Your boiler has detected that it cannot safely remove waste combustion gases, so it has shut itself down to prevent a carbon monoxide hazard.
Your boiler has automatically turned itself off because it has become too hot inside, likely due to a lack of water flow.
Your boiler has detected that the exhaust gases are getting too hot and has automatically shut itself down to prevent damage.
Your boiler has lost the ability to accurately measure the temperature of the water used for your radiators, causing it to shut down to prevent overheating.
Your boiler is struggling to accurately measure the temperature of the water returning to it, which prevents the system from heating your home properly.
Your boiler has detected an issue with the sensor that monitors the temperature of the exhaust gases, and it has stopped working for safety reasons.
Your boiler has blocked itself because it has been reset too many times while trying to fix a persistent underlying fault.
Your boiler has stopped working because the amount of water inside your central heating system has dropped too low.
Your boiler's computer system is experiencing a software glitch that is preventing it from running properly.
Your boiler has stopped working because it cannot light the internal flame or keep it burning.
Your boiler is struggling to register your button presses, which usually means the control panel interface has become unresponsive or stuck.
Your boiler has lost its connection to the remote thermostat or controller, meaning it may not be receiving instructions to turn the heating on or off.
Your boiler was running but the flame unexpectedly went out, so it has shut down as a safety precaution.
Your boiler has tried to start but could not ignite the flame, so it has locked itself out for safety.
BoilerFaultCodes