F19 High

Saunier Duval F19 Fault Code

The Saunier Duval F19 fault code means: your boiler has lost its connection to the sensor that monitors heating temperature, so it has stopped running as a safety precaution.. It appears on 6 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 thermistor unplugged. Thermistor cable defective/broken, thermistor faulty. Check that thermistor attached correctly to pipe

What causes the Saunier Duval F19 fault?

This fault occurs when the boiler's internal computer loses communication with the sensor that monitors the temperature of the water sent to your radiators. The most common cause is the sensor itself failing due to age or internal wear, though it can also be triggered by a loose or damaged wiring connection inside the unit.

This fault is often more frequent during the autumn and winter months when the boiler is suddenly under higher demand after being inactive during the summer.

Typical repair cost £90-160 (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 F19 fault code

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

Source

Saunier Duval F19 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