How much does it cost to fix Chaffoteaux error code 8.iii?

Typical repair cost for the Chaffoteaux 8.iii fault is £150-300 including labour.

8.iii Medium

Chaffoteaux 8.iii Fault Code

Q: What does the Chaffoteaux 8.iii fault code mean?

Your boiler's water circulation system has become clogged with internal sludge or debris, making the pump struggle and create a grinding or rattling noise.

Also written as 8III — same fault.

The Chaffoteaux 8.iii fault code means: your boiler's water circulation system has become clogged with internal sludge or debris, making the pump struggle and create a grinding or rattling noise.. It appears on 3 Chaffoteaux models in our database.

Technical description: Pump noisy - Debris in pump

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 8.iii fault code

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

Source

Chaffoteaux 8.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