How much does it cost to fix boiler error code K1?

Typical repair cost for the boiler K1 fault is £100-200 including labour.

K1 High

Boiler Fault Code K1

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code K1 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 safety guard protecting the flue terminal is missing or incorrectly installed, which prevents the boiler from starting safely. (As reported on Ideal Classic NF)

Pick your boiler brand for the K1 fix

Ideal K1 1 model

Source

Information for the K1 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