Low
d.08 on Vaillant ecoFIT Pure 425

Your boiler is operating normally but is currently showing whether your external room thermostat is telling the heating to be on or off.

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

Status of the 230V thermostat (0=Room thermostat open, 1=Room thermostat closed)

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 29.
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

Check if your wall thermostat or programmer is turned up higher than the current room temperature.Replace the batteries in your wireless room thermostat if the screen is blank.Ensure the heating schedule on your timer is set to an 'ON' period.

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