BoilerFaultCodesSaunier Duval F7 Fault Code
The Saunier Duval F7 fault code means: your boiler has detected a problem with the sensor that monitors hot water temperature, which typically means you will have little or no hot water.. It appears on 6 Saunier Duval models in our database.
Technical description: DHW thermistor fault
What causes the Saunier Duval F7 fault?
This fault occurs when the boiler's internal computer loses communication with the sensor that monitors your hot water temperature. The most common reason is that the sensor has physically failed due to age or internal wear, though it can also be triggered by loose or corroded electrical connections between the sensor and 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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Gas Safe Register →Saunier Duval models that show the F7 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Saunier Duval F7 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 27 April 2026