High
10 on Saunier Duval Isofast

Your boiler has detected that the internal exhaust fan is not spinning correctly, which stops the system from operating to ensure safe ventilation.

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

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

F11View →F12View →

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