How much does it cost to fix boiler error code F.25?

Typical repair cost for the boiler F.25 fault is £120-350 including labour.

F.25 High

Boiler Fault Code F.25

Also written as F25 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code F.25 appears across 2 boiler brands and 51 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected an electrical connection issue or a sudden temperature rise, causing it to shut down for safety. (As reported on Vaillant ecoTEC)

Pick your boiler brand for the F.25 fix

Glow-worm F.25 6 models Vaillant F.25 45 models

Source

Information for the F.25 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

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