How much does it cost to fix boiler error code 66C?

Typical repair cost for the boiler 66C fault is £120-280 including labour.

66C High

Boiler Fault Code 66C

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 66C appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped working because it cannot confirm that the fan is safely pushing exhaust fumes out of the flue. (As reported on Worcester Bosch WR325 RSF)

Pick your boiler brand for the 66C fix

Worcester Bosch 66C 1 model

Source

Information for the 66C 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