BoilerFaultCodes E00-684 High
Boiler Fault Code E00-684
Also written as E00684 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E00-684 appears across 2 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to detect the movement of water inside the system, which is preventing it from safely starting up to provide heat or hot water. (As reported on Ideal Mini HE)
Pick your boiler brand for the E00-684 fix
Source
Information for the E00-684 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