BoilerFaultCodes 304 Medium
Boiler Fault Code 304
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 304 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 has attempted to restart itself too many times in a short period and has temporarily locked you out for safety. (As reported on Ariston Alteas One)
Pick your boiler brand for the 304 fix
Source
Information for the 304 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