BoilerFaultCodes D.018 Low
Boiler Fault Code D.018
Also written as D018 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.018 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 currently running a check on its internal water pump to ensure water is circulating correctly throughout your heating system. (As reported on Vaillant ecoTEC Pro 28)
Pick your boiler brand for the D.018 fix
Source
Information for the D.018 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