How much does it cost to fix boiler error code FSK1?

Typical repair cost for the boiler FSK1 fault is £80-150 including labour.

FSK1 Low

Boiler Fault Code FSK1

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code FSK1 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 detected that the external frost protection kit has been triggered, which means the system is attempting to protect itself from freezing temperatures. (As reported on Warmflow Kabin Pak and Utility)

Pick your boiler brand for the FSK1 fix

Warmflow FSK1 1 model

Source

Information for the FSK1 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 7 July 2026