Low
D.066 on Vaillant ecoTEC Plus 836

Your boiler is currently trying to keep a small amount of water pre-heated so you get hot water faster when you turn on the tap.

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

Warmstartactivation

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 75.
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

This is an operational status message rather than a fault codeIf you wish to disable this feature to save energy, locate the 'Warmstart' button on your boiler control panelPress the button to toggle the setting to 'off' if you prefer the boiler to only heat water on demand

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