BoilerFaultCodes A39 High
Boiler Fault Code A39
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code A39 appears across 1 boiler brand and 2 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 malfunctioning, which means the system cannot safely regulate its operations. (As reported on Ariston Bravo 24 MFFI)
Pick your boiler brand for the A39 fix
Source
Information for the A39 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