How much does it cost to fix Saunier Duval error code F3?

Typical repair cost for the Saunier Duval F3 fault is £150-300 including labour.

F3 High

Saunier Duval F3 Fault Code

Q: What does the Saunier Duval F3 fault code mean?

Your boiler is struggling to clear exhaust gases out of the flue, so it has safely shut itself down to prevent fumes from building up.

The Saunier Duval F3 fault code means: your boiler is struggling to clear exhaust gases out of the flue, so it has safely shut itself down to prevent fumes from building up.. It appears on 4 Saunier Duval models in our database.

Technical description: Air pressure switch fault (repeated)

Typical repair cost £150-300 (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 F3 fault code

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

Enviroplus Repair: £150-300
Isofast Repair: £150-300
Thema F 30 E Plus Repair: £120-250
Themaclassic Plus F30E Repair: £150-300

Source

Saunier Duval F3 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