Low
d.05 on Vaillant ecoTEC sustain

The d.05 code is not actually an error; it is a normal status message showing the temperature your boiler is currently aiming to reach for your radiators.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Determined heating flow set target temperature: Current value

From this model's manual
Verified against the Vaillant Ecotec Sustain installation & service manual, page 46.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

No action requiredThis is a status code confirming your boiler is operating normallyPress the 'i' button on the front panel to return to the standard display

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