How much does it cost to fix Saunier Duval error code 2 5?

Typical repair cost for the Saunier Duval 2 5 fault is £150-300 including labour.

2 5 High

Saunier Duval 2 5 Fault Code

Q: What does the Saunier Duval 2 5 fault code mean?

Your boiler is shutting down because the water inside is heating up much faster than the system can move it around, which suggests a blockage or a pump issue.

Also written as 25 — same fault.

The Saunier Duval 2 5 fault code means: your boiler is shutting down because the water inside is heating up much faster than the system can move it around, which suggests a blockage or a pump issue.. It appears on 2 Saunier Duval models in our database.

Technical description: The rate of temperature rise measured by the heating flow thermistor is too high.

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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Saunier Duval models that show the 2 5 fault code

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

Source

Saunier Duval 2 5 fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026