How much does it cost to fix Chaffoteaux error code YELLOW FLAMES / SOOT FORMED?

Typical repair cost for the Chaffoteaux YELLOW FLAMES / SOOT FORMED fault is £120-250 including labour.

YELLOW FLAMES / SOOT FORMED Emergency

Chaffoteaux YELLOW FLAMES / SOOT FORMED Fault Code

Q: What does the Chaffoteaux YELLOW FLAMES / SOOT FORMED fault code mean?

Your boiler is not burning fuel correctly, which is creating dangerous soot and could potentially release harmful carbon monoxide into your home.

Also written as YELLOWFLAMESSOOTFORMED — same fault.

The Chaffoteaux YELLOW FLAMES / SOOT FORMED fault code means: your boiler is not burning fuel correctly, which is creating dangerous soot and could potentially release harmful carbon monoxide into your home.. It appears on 8 Chaffoteaux models in our database.

Technical description: I) Heating body fins blocked; II) Primary air supply restricted; III) Wrong injectors

Typical repair cost £120-250 (including labour)

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Chaffoteaux models that show the YELLOW FLAMES / SOOT FORMED fault code

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

Source

Chaffoteaux YELLOW FLAMES / SOOT FORMED 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