Frequent sooting (5) Emergency

Chaffoteaux Frequent sooting (5) Fault Code

Also written as FREQUENTSOOTING5 — same fault.

The Chaffoteaux Frequent sooting (5) fault code means: your boiler is struggling to burn fuel correctly because the internal parts that manage the gas supply are not the correct size, which is causing dangerous carbon build-up.. It appears on 1 Chaffoteaux model 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: Wrong injectors fitted.
Typical repair cost £180-350 (including labour)

Engineer required

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

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Chaffoteaux models that show the Frequent sooting (5) fault code

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

Source

Chaffoteaux Frequent sooting (5) fault code information on this page is sourced and cross-checked against the official Chaffoteaux service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026