High
Red light F ON on Saunier Duval SD 30e

Your boiler has detected a safety issue and has automatically switched itself off to prevent damage or dangerous operation.

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

Boiler will not work. Depress the boiler safety cutoff reset button G

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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