BoilerFaultCodes CN12 High
Boiler Fault Code CN12
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code CN12 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 lost its specific configuration settings, meaning it has forgotten how to correctly control your heating and hot water. (As reported on Baxi Suprima 100)
Pick your boiler brand for the CN12 fix
Source
Information for the CN12 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