BoilerFaultCodes E099 High
Boiler Fault Code E099
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E099 appears across 1 boiler brand and 10 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 that the water temperature difference between the outgoing and incoming pipes is outside of the normal expected range, causing it to shut down to prevent damage. (As reported on Vokera Vision System Sgc)
Pick your boiler brand for the E099 fix
Source
Information for the E099 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