BoilerFaultCodes d.28 Medium
Boiler Fault Code d.28
Also written as D28 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code d.28 appears across 2 boiler brands and 22 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 communicate with an external accessory, such as an additional pump or timer, which might be preventing your heating or hot water from working correctly. (As reported on Vaillant ecoFIT Pure 830)
Pick your boiler brand for the d.28 fix
Source
Information for the d.28 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