d.81 Low

Boiler Fault Code d.81

Also written as D81 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code d.81 appears across 3 boiler brands and 41 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 hot water system has been running; it is not a fault and your boiler is operating normally. (As reported on Vaillant ecoMAX System 612)

Pick your boiler brand for the d.81 fix

Glow-worm d.81 8 models Heatline d.81 7 models Vaillant d.81 26 models

Source

Information for the d.81 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