What does the Vaillant F.25 fault code mean?

Your boiler has detected that the gases it is producing are too hot to be safe, so it has automatically shut down to prevent damage.

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

Typical repair cost for the Vaillant F.25 fault is £150-350 including labour.

Safety switch-off: Flue gas temperature too high

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.

7 signs repair isn't worth it anymore.