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S.11 on Glow-worm Flexicom cx

Your boiler is performing a routine safety check by running the fan before the burner ignites.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

fan pre-run

What causes this fault?

This status occurs when the boiler prepares for ignition by clearing out the combustion chamber. The fan spins up to ensure there is a safe flow of fresh air and to remove any residual gases before the burner light. It is a fundamental part of the boiler's start-up sequence and not a sign of a mechanical failure.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Related fault codes

S.01View →S.02View →S.03View →

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