High Lockout
F3 on Keston S30

Your boiler has detected an issue with its fan, meaning it cannot safely circulate air or clear exhaust fumes and has shut down as a safety precaution.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

What causes this fault?

This fault occurs when the boiler's internal computer is unable to communicate with or control the fan, which is essential for pushing harmful exhaust gases out of the flue. The most common reason is that the fan motor has physically burnt out or stopped spinning, though it can also be triggered by loose electrical connections or a fault on the main control board.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F1View →L2View →

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