17 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 47-077-30 | 636 COMBI 36 | 2018–present |
| 47-077-31 | 636 COMBI LPG | 2020–present |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
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Your boiler has detected an internal electronic or sensor issue and has safely shut down to prevent any potential hazards.
Your boiler has detected an internal communication or general operating fault that prevents it from running safely and efficiently.
Your boiler has detected an internal hardware error that prevents it from operating safely.
Your boiler has detected an internal electrical or sensor problem and has safely shut down to prevent any issues.
Your boiler has detected an internal hardware error involving one of its main operating components, which will cause it to stop working until it is checked.
Your boiler has detected an internal communication or sensor issue and has safely shut down to prevent any potential risks.
Your boiler has temporarily shut down because the water inside it has become too hot.
Your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.
Your boiler has detected that the water inside the system is either not heating up properly or is getting far too hot, very quickly.
Your boiler has temporarily stopped working because the gas flame went out while it was running.
Your boiler has detected an internal electronics or safety fault that requires a trained professional to safely diagnose and resolve.
Your boiler has failed to light because it cannot detect a steady gas flame to keep it running.
Your boiler has stopped working because it cannot detect a flame or the gas supply to it has been interrupted.
Your boiler has failed to light because it is not detecting a steady gas supply or a flame.
Your boiler has detected an internal electrical or component error that requires a professional inspection to resolve safely.
Your boiler has detected an internal electronic or component error that requires a professional inspection to resolve safely.
Your boiler has detected an internal electronic or flame stability error and has safely shut down to prevent further issues.
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BoilerFaultCodes