Low
d.16 on Vaillant ecoFIT Pure 418

This is a normal status message showing whether your room thermostat is currently telling the boiler to turn the heating on or off, rather than a system fault.

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

Check if your room thermostat is set to a temperature higher than the current room temperature.Replace the batteries in your wall-mounted thermostat if the screen is blank.Ensure the heating programmer or app is set to an 'On' period.

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