BoilerFaultCodes C1 05 Low
Boiler Fault Code C1 05
Also written as C105 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code C1 05 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 is currently running an automatic cycle to clear trapped air from the system, which typically occurs after it has been powered on or refilled. (As reported on Atag Sov.)
Pick your boiler brand for the C1 05 fix
Source
Information for the C1 05 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