How much does it cost to fix boiler error code D.020?

Typical repair cost for the boiler D.020 fault is £90-180 including labour.

D.020 Low

Boiler Fault Code D.020

Also written as D020 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code D.020 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 set to an abnormally high hot water temperature limit, which usually indicates that the system is simply waiting for a sensor to signal that the water is hot enough. (As reported on Vaillant ecoTEC Pro)

Pick your boiler brand for the D.020 fix

Vaillant D.020 7 models

Source

Information for the D.020 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