How much does it cost to fix Chaffoteaux error code 8.4?

Typical repair cost for the Chaffoteaux 8.4 fault is £120-250 including labour.

8.4 High

Chaffoteaux 8.4 Fault Code

Q: What does the Chaffoteaux 8.4 fault code mean?

Your boiler is failing to keep its small pilot flame lit, which prevents the main burner from igniting and stops your heating and hot water from working.

Also written as 84 — same fault.

The Chaffoteaux 8.4 fault code means: your boiler is failing to keep its small pilot flame lit, which prevents the main burner from igniting and stops your heating and hot water from working.. It appears on 4 Chaffoteaux models in our database.

Technical description: Pilot will not stay alight

Typical repair cost £120-250 (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 8.4 fault code

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

Source

Chaffoteaux 8.4 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