Low
D.129 on Vaillant ecoTEC plus System

Your boiler is flagging that the temperature setting for your hot water has been set lower than the system's safe operating limits.

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

Minimumdomestichotwatertarget value

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 76.
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

Locate the hot water temperature dial or digital menu on your boiler front panelIncrease the domestic hot water target temperature setting to at least 50-60 degrees CelsiusRestart the boiler to clear the code

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