Low
d.66 on Vaillant Home Combi

Your boiler is simply indicating that the 'warm start' feature is active, which keeps a small amount of water hot so your taps run warm more quickly.

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

Activationofthewarmstartfunctionforhotwater

From this model's manual
Verified against the Vaillant Home Combi installation & service manual, page 33.
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 'warm start' button or menu setting on your boiler displayPress or select the option to turn it 'off' if you wish to disable the featureConfirm the display now shows the standard operating status

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