BoilerFaultCodes AA 9988 High
Boiler Fault Code AA 9988
Also written as AA9988 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code AA 9988 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's computer is having trouble communicating internally, which has caused it to stop working to ensure your safety. (As reported on Ariston Clas One)
Pick your boiler brand for the AA 9988 fix
Source
Information for the AA 9988 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