Low
d.01 on Vaillant ecoFIT Pure 435

Your boiler is continuing to run its internal pump after the heating has switched off to safely cool down the heat exchanger.

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

Pump overrun in heating mode

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 that at least one radiator (usually one without a plastic thermostatic valve) is turned fully open to allow water flow.Ensure your external heating controls or room thermostat are set to your desired temperature.Wait for the boiler to complete this cycle; it is a normal safety function and the code will disappear once the system has cooled.

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