Low
d.43 on Vaillant ecoFIT Pure 835

Your boiler is notifying you that it is using an automatic setting to adjust its heat output based on the outdoor 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

Heating curve

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 31.
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 external temperature sensor is obstructed or dirtyAdjust the heating curve setting via the control panel if the house is too cold or too warmConsult your thermostat manual to ensure the weather compensation settings match your comfort needs

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