How much does it cost to fix boiler error code F.33?

Typical repair cost for the boiler F.33 fault is £120-250 including labour.

F.33 High

Boiler Fault Code F.33

Also written as F33 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code F.33 appears across 2 boiler brands and 31 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has sensed it is too cold and the fan is stuck trying to protect the internal pipes from freezing. (As reported on Glow-worm Energy)

Pick your boiler brand for the F.33 fix

Glow-worm F.33 6 models Vaillant F.33 25 models

Source

Information for the F.33 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