Emergency Lockout
F16 on Saunier Duval Isotwin F30E

Your boiler is still detecting a flame even after it has been told to turn off, which is a safety concern that requires a professional inspection.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Flame detection fault (flame presence for more than 5 seconds after burner stopped). Gas valve defective

What causes this fault?

This fault occurs when the boiler's safety sensors continue to detect heat or electrical signals from a flame even after the gas should have been cut off. The most common reasons are a sticking gas valve that isn't closing fully, a damaged sensor probe that is sending incorrect signals, or a fault within the main control board.

Engineer required

This is a emergency 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

F4View →F1View →F14View →

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