5.viii High

Chaffoteaux 5.viii Fault Code

Also written as 5VIII — same fault.

The Chaffoteaux 5.viii fault code means: your boiler is struggling to heat water because it is not receiving enough gas to reach the required temperature.. It appears on 3 Chaffoteaux models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Hot water does not operate over temperature range - Low inlet gas pressure
Typical repair cost £100-250 (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 5.viii fault code

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

Source

Chaffoteaux 5.viii 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