BoilerFaultCodes EE 9999 High
Boiler Fault Code EE 9999
Also written as EE9999 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code EE 9999 appears across 1 boiler brand and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's main control computer is experiencing a general communication error, causing the system to stop working as a safety precaution. (As reported on Ariston E-Combi One 30)
Pick your boiler brand for the EE 9999 fix
Source
Information for the EE 9999 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