Low
d.08 on Vaillant ecoFIT Pure 435

Your boiler is waiting for a signal from your thermostat to tell it to turn on, which means the heating is currently switched off or the room has reached the desired temperature.

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 room thermostat is turned up high enough to call for heatReplace the batteries in your wireless wall thermostat or programmerEnsure your heating timer or smart app is set to an 'On' period

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Related fault codes

d.00View →d.07View →

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