Emergency
Boiler sooting on Ferroli Sigma 40 FF

Your boiler is struggling to burn the gas cleanly, which can lead to a dangerous buildup of soot and harmful fumes inside the appliance.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

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

What the manual says

Manufacturer manual

Faulty flame adjustment. Check that the burner flame is adjusted correctly and that gas consumption is correct for the boiler output. Burner air ports blocked. Clear air ports

From this model's manual
Verified against the Ferroli Sigma 40 Ff installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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