F04 Emergency

Ferroli F04 Fault Code

The Ferroli F04 fault code means: your boiler has detected that hot combustion gases are not venting away correctly and has safely shut down to prevent the risk of carbon monoxide poisoning.. It appears on 3 Ferroli models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Fume thermostat or generic safety activation
Typical repair cost £150-350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Ferroli models that show the F04 fault code

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

Source

Ferroli F04 fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026