A09 High

Boiler Fault Code A09

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code A09 appears across 3 boiler brands and 17 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has sensed it is getting much too hot and has shut itself down to prevent damage or dangerous overheating. (As reported on Ferroli Bluehelix Tech)

Pick your boiler brand for the A09 fix

Ariston A09 9 models Ferroli A09 7 models Vokera A09 1 model

Source

Information for the A09 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