3 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
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 |
|---|---|---|
| 47-311-19 | High Flow 400 BF | 1997–2002 |
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Your boiler has lost the signal from one of its internal heat sensors, meaning it cannot accurately monitor the temperature and has shut down to stay safe.
Your boiler is sensing a flame even though the gas should be turned off, leading the system to shut down as a safety precaution.
Your boiler is unable to safely drain away the water it creates during normal operation, causing it to block its own internal system and switch off.
BoilerFaultCodes