BoilerFaultCodes C4 237 High
Boiler Fault Code C4 237
Also written as C4237 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code C4 237 appears across 1 boiler brand and 11 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's computer system has encountered a critical communication error and can no longer safely operate the heating or hot water, requiring professional repair. (As reported on Worcester Bosch Greenstar i)
Pick your boiler brand for the C4 237 fix
Source
Information for the C4 237 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