How much does it cost to fix Chaffoteaux error code 9.iii?

Typical repair cost for the Chaffoteaux 9.iii fault is £150-300 including labour.

9.iii Emergency

Chaffoteaux 9.iii Fault Code

Q: What does the Chaffoteaux 9.iii fault code mean?

Your boiler is overheating because it is burning more gas than it can safely process, causing the internal system to shut down to prevent damage.

Also written as 9III — same fault.

The Chaffoteaux 9.iii fault code means: your boiler is overheating because it is burning more gas than it can safely process, causing the internal system to shut down to prevent damage.. It appears on 3 Chaffoteaux models in our database.

Technical description: Excessive temperature rise across boiler - Gas rate too high

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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Chaffoteaux models that show the 9.iii fault code

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

Source

Chaffoteaux 9.iii 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