BoilerFaultCodes d.15 High
Boiler Fault Code d.15
Also written as D15 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code d.15 appears across 2 boiler brands and 16 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 circulate water properly because the internal pump is not responding as expected, which will prevent your heating and hot water from working correctly. (As reported on Vaillant ecoFIT Pure 835)
Pick your boiler brand for the d.15 fix
Source
Information for the d.15 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