BoilerFaultCodesSaunier Duval F16 Fault Code
The Saunier Duval F16 fault code means: 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.. It appears on 3 Saunier Duval models in our database.
Technical description: Flame detection fault (flame presence for more than 5 seconds after burner stopped). Gas valve defective
What causes the Saunier Duval F16 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Saunier Duval models that show the F16 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Saunier Duval F16 fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026