BoilerFaultCodes D.75 High
Boiler Fault Code D.75
Also written as D75 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.75 appears across 2 boiler brands and 23 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has stopped heating your hot water tank because it has been running for too long without reaching the target temperature, likely due to a sensor or flow issue. (As reported on Vaillant ecoTEC plus VU GB 656/4-5 A)
Pick your boiler brand for the D.75 fix
Source
Information for the D.75 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 31 August 2026