Low
d.23 on Vaillant ecoFIT Pure 435

This is a normal status code indicating whether your central heating is currently requested 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 heating demand (off=Heating off, on=Heating on)

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 30.
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 or programmer is set to a temperature higher than the current room temperatureEnsure the heating function is enabled on the boiler control panelNo action is required if the heating is working as intended, as this is an information code rather than a fault

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