BoilerFaultCodes d.45 Low
Boiler Fault Code d.45
Also written as D45 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code d.45 appears across 1 boiler brand and 20 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is displaying a background setting related to how it calculates the water temperature, but this is an information display for an engineer rather than a functional fault. (As reported on Vaillant ecoFIT Pure 412)
Pick your boiler brand for the d.45 fix
Source
Information for the d.45 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