1C High

Boiler Fault Code 1C

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 1C 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 a safety sensor meant to monitor exhaust gases is disconnected or has failed, causing the system to shut down for protection. (As reported on Ideal Maximiser SE)

Pick your boiler brand for the 1C fix

Ideal 1C 1 model

Source

Information for the 1C 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