BoilerFaultCodes 704 High
Boiler Fault Code 704
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 704 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 detected an internal communication error between its main control boards, meaning it can no longer send or receive instructions correctly. (As reported on Ariston Alteas One)
Pick your boiler brand for the 704 fix
Source
Information for the 704 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