BoilerFaultCodes D.029 Medium
Boiler Fault Code D.029
Also written as D029 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.029 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected that the water is not flowing around your heating system fast enough, which often points to a blockage, trapped air, or a struggling pump. (As reported on Vaillant ecoTEC Pro 24)
Pick your boiler brand for the D.029 fix
Source
Information for the D.029 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