BoilerFaultCodesBritish Gas F4 Fault Code
The British Gas F4 fault code means: your boiler is lighting up, but the flame is cutting out shortly after, meaning your heating and hot water will not stay on.. It appears on 1 British Gas model in our database.
Technical description: Flame goes out whilst lit during a demand (displayed as 'ign')
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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British Gas models that show the F4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
British Gas F4 fault code information on this page is sourced and cross-checked against the official British Gas service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026