BoilerFaultCodes E01-604 High
Boiler Fault Code E01-604
Also written as E01604 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E01-604 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's internal computer is experiencing a communication error and is unable to safely coordinate the heating and hot water process. (As reported on Worcester Bosch 24i RSF)
Pick your boiler brand for the E01-604 fix
Source
Information for the E01-604 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 7 July 2026