26 Medium

Chaffoteaux 26 Fault Code

The Chaffoteaux 26 fault code means: your boiler has detected a problem with the temperature sensor for the hot water storage cylinder, meaning it cannot accurately monitor the water temperature.. It appears on 3 Chaffoteaux models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Thermistor cylinder bypassed
Typical repair cost £90-160 (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 26 fault code

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

Source

Chaffoteaux 26 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 7 July 2026