Low
d.17 on Vaillant ecoFIT Pure 435

Your boiler is currently set to measure the temperature of the water returning to the unit rather than the water flowing out to your radiators.

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 control (off=Flow temperature, on=Return temperature)

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

Navigate to the diagnostic menu on the displayIdentify parameter d.17Change the value from 1 (on) to 0 (off) if you prefer standard flow temperature control

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d.00View →d.01View →d.18View →

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