How much does it cost to fix Ideal error code b 25?

Typical repair cost for the Ideal b 25 fault is £150-300 including labour.

b 25 High

Ideal b 25 Fault Code

Q: What does the Ideal b 25 fault code mean?

Your boiler is heating up much faster than normal and has shut down to prevent internal damage or overheating.

Also written as B25 — same fault.

The Ideal b 25 fault code means: your boiler is heating up much faster than normal and has shut down to prevent internal damage or overheating.. It appears on 1 Ideal model in our database.

Technical description: Flow temperature rise too fast

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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Ideal models that show the b 25 fault code

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

Imax W Repair: £150-300

Source

Ideal b 25 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

Ideal Imax W manual (PDF)

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026