BoilerFaultCodes 273 C4 Medium
Boiler Fault Code 273 C4
Also written as 273C4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 273 C4 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 has detected that the internal fan is running when it should be idle, often caused by a communication error or a sensor glitch. (As reported on Worcester Bosch Greenstar 12i System)
Pick your boiler brand for the 273 C4 fix
Source
Information for the 273 C4 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