Low
d.02 on Vaillant ecoFIT Pure 435

Your boiler is taking a short, programmed energy-saving break to prevent the burner from turning on and off too frequently.

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

Burner anti-cycling time 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 your radiator valves (TRVs) are open to allow heat to circulateEnsure your room thermostat is set to a temperature higher than the current room temperatureWait 10-15 minutes for the countdown timer to finish, as the boiler will restart automatically

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