BoilerFaultCodes D.074 Low
Boiler Fault Code D.074
Also written as D074 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.074 appears across 1 boiler brand 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 currently running a routine high-temperature cycle designed to kill bacteria in your hot water storage tank, which is a normal part of its maintenance program. (As reported on Vaillant ecoTEC Pro 30)
Pick your boiler brand for the D.074 fix
Source
Information for the D.074 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