BoilerFaultCodes E01-840 High
Boiler Fault Code E01-840
Also written as E01840 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E01-840 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 lost water pressure, and the internal component used to refill it is likely disconnected or faulty. (As reported on Worcester Bosch 24/28CDi II RSF)
Pick your boiler brand for the E01-840 fix
Source
Information for the E01-840 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