F6 High

Saunier Duval F6 Fault Code

The Saunier Duval F6 fault code means: your boiler has temporarily stopped working because it cannot accurately measure the temperature of the water flowing through your heating system.. It appears on 2 Saunier Duval models in our database.

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: Central heating flow thermistor fault
Typical repair cost £120-250 (including labour)

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 F6 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Saunier Duval F6 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 31 August 2026