BoilerFaultCodes 9F856 High
Boiler Fault Code 9F856
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 9F856 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has stopped working because it has been reset too many times while trying to clear a burner fault, and it has now locked itself for safety. (As reported on Worcester Bosch Greenstar Heatslave II)
Pick your boiler brand for the 9F856 fix
Source
Information for the 9F856 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