Low
d.09 on Vaillant ecoFIT Pure 835

This is a status code rather than a fault, simply showing the temperature your external room thermostat is asking the boiler to reach.

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

Heating flow set target temperature that is set on the eBUS room thermostat

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 your room thermostat or smart phone app to ensure the heating is set to your desired temperatureReplace the batteries in your room thermostat if the display is blankEnsure the thermostat is communicating with the boiler

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