BoilerFaultCodes c 1 05 Low
Boiler Fault Code c 1 05
Also written as C105 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code c 1 05 appears across 1 boiler brand and 3 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 automated air-removal cycle to clear trapped air from the system, which is a normal process after maintenance or a power restart. (As reported on Atag Q 25CR)
Pick your boiler brand for the c 1 05 fix
Source
Information for the c 1 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