BoilerFaultCodes Incorrect CO2 Emergency
Boiler Fault Code Incorrect CO2
Also written as INCORRECTCO2 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Incorrect CO2 appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to mix the right amount of air with its fuel to burn cleanly, which means it may not operate safely or efficiently. (As reported on Worcester Bosch Utility)
Pick your boiler brand for the Incorrect CO2 fix
Source
Information for the Incorrect CO2 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