BoilerFaultCodes 256 High
Boiler Fault Code 256
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 256 appears across 1 boiler brand and 6 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 an internal computer error that prevents it from operating, and it requires a professional engineer to reset or replace the control board. (As reported on Worcester Bosch Greenstar 12i System)
Pick your boiler brand for the 256 fix
Source
Information for the 256 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 7 July 2026