BoilerFaultCodes 00h - FFh Low
Boiler Fault Code 00h - FFh
Also written as 00HFFH — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 00h - FFh appears across 1 boiler brand and 2 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 through its normal internal health check or diagnostic display mode and is not currently reporting a specific malfunction. (As reported on Worcester Bosch Greenstar 25i (ZWB 7-25))
Pick your boiler brand for the 00h - FFh fix
Source
Information for the 00h - FFh 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