A04 High

Boiler Fault Code A04

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code A04 appears across 4 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 detected an internal electrical fault with the component that controls the gas supply, meaning it cannot safely ignite for heating or hot water. (As reported on Vokera Condexa Pro)

Pick your boiler brand for the A04 fix

Ariston A04 7 models Ferroli A04 8 models Potterton A04 1 model Vokera A04 1 model

Source

Information for the A04 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