Low
d.16 on Vaillant ecoFIT Pure 435

This is a normal status screen showing whether your thermostat is currently telling the boiler to turn the heating 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 24V room thermostat (off=Heating off, on=Heating on)

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

Turn your room thermostat up to check if the status changes from 'off' to 'on'Check batteries in your wireless thermostat if the boiler isn't respondingEnsure your heating programmer or app is set to an 'on' period

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