BoilerFaultCodes 599 Medium
Boiler Fault Code 599
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 599 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 is struggling to transfer heat to your hot water taps, which likely means the internal water-heating component has become clogged with debris or limescale. (As reported on Warmflow 70/90 Combi)
Pick your boiler brand for the 599 fix
Source
Information for the 599 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