Low
D.2 on Vaillant ecoTEC System

Your boiler is temporarily resting because it has reached its target temperature and is waiting for a short period before restarting to prevent unnecessary wear and tear.

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

Max burner anti-cycling period at 20c flow temperature

From this model's manual
Verified against the Vaillant Ecotec installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This occurs when your boiler reaches its target heat and shuts off to prevent the system from overheating or wasting energy. Rather than turning on and off rapidly, which can damage internal components, the boiler enters a programmed 'resting' phase until the water temperature drops enough to justify restarting. This is a normal safety and efficiency feature rather than a mechanical failure.

This status is more frequent during mild spring or autumn days when your radiators don't need maximum heat to keep your home warm.

DIY fix possible

Check that your room thermostat or programmer is set to a high enough temperatureOpen any radiator valves (TRVs) fully in the room with the main thermostatWait 15 minutes to see if the status code clears and the boiler fires back up automatically

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