F3 High

British Gas F3 Fault Code

The British Gas F3 fault code means: your boiler has detected that the internal component responsible for clearing exhaust gases is not operating correctly, so it has safely shut down to prevent any unsafe buildup.. It appears on 1 British Gas model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Fan fault (displayed as 'fAn')
Typical repair cost £180-350 (including labour)

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 F3 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

British Gas F3 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