How much does it cost to fix Chaffoteaux error code 25?

Typical repair cost for the Chaffoteaux 25 fault is £120-200 including labour.

25 High

Chaffoteaux 25 Fault Code

Q: What does the Chaffoteaux 25 fault code mean?

Your boiler is failing to detect the temperature of your hot water cylinder, which means it will likely stop providing hot water until the faulty sensor is replaced.

The Chaffoteaux 25 fault code means: your boiler is failing to detect the temperature of your hot water cylinder, which means it will likely stop providing hot water until the faulty sensor is replaced.. It appears on 4 Chaffoteaux models in our database.

Technical description: Thermistor cylinder open

Typical repair cost £120-200 (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 25 fault code

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

Calydra 100 Repair: £120-200
Calydra 23 Green Repair: £120-£190
Calydra 24 Green Repair: £90-160
Serelia 24 MFFI Repair: £120-200

Source

Chaffoteaux 25 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