BoilerFaultCodes D.035 High
Boiler Fault Code D.035
Also written as D035 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.035 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 struggling to switch between providing heating for your radiators and heating your hot water, which may result in a loss of one or both services. (As reported on Vaillant ecoTEC Pro 30)
Pick your boiler brand for the D.035 fix
Source
Information for the D.035 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