Boiler Fault Code d.81

Also written as D81 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026

Fault code d.81 appears across 3 boiler brands and 39 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning This code is simply an information display showing the total number of hours your boiler has spent actively producing hot water, rather than a fault indicating a problem. (As reported on Vaillant ecoFIT Pure 830)