BoilerFaultCodes Er99 High
Boiler Fault Code Er99
Also written as ER99 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Er99 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 lost its configuration settings or isn't receiving power correctly, meaning it doesn't know which specific model it is supposed to be. (As reported on Biasi Activa)
Pick your boiler brand for the Er99 fix
Source
Information for the Er99 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