How much does it cost to fix boiler error code D.51?

Typical repair cost for the boiler D.51 fault is £80-160 including labour.

D.51 Low

Boiler Fault Code D.51

Also written as D51 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code D.51 appears across 2 boiler brands and 26 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is flagging a minor technical adjustment error regarding its internal fan speed settings. (As reported on Vaillant ecoTEC)

Pick your boiler brand for the D.51 fix

Glow-worm D.51 7 models Vaillant D.51 19 models

Source

Information for the D.51 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