4 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 |
|---|---|---|
| 47-311-34 | 28 Cdi RSF | 1997–2005 |
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Your boiler is struggling because the internal water pump is stuck or cannot circulate water properly, preventing your heating and hot water from working.
Your boiler's computer is having trouble communicating with an internal part, which prevents the system from starting up safely.
Your boiler has stopped working because the internal fan isn't spinning fast enough to safely clear away exhaust fumes.
Your boiler is struggling to accurately measure the temperature of the water, which means it has safely shut down to prevent overheating.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes