BoilerFaultCodes 55 -- 55 Medium
Boiler Fault Code 55 -- 55
Also written as 5555 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 55 -- 55 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 at its absolute maximum capacity because it has been set to a special testing mode, rather than operating normally to heat your home. (As reported on Worcester Bosch Greenstar 25HE)
Pick your boiler brand for the 55 -- 55 fix
Source
Information for the 55 -- 55 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