Low
S.0 on Vaillant ecoTEC exclusive

Your boiler is working perfectly; it is simply in standby mode because your thermostat hasn't asked it to turn on for heating or hot water yet.

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

No heat required

Shared across the ecoTEC exclusive range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s 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 code appears when the boiler is powered on and ready to work, but your thermostat or timer is not currently asking for heat. It signifies that the internal sensors have confirmed all systems are safe and the unit is simply waiting for a signal to start the burner. Once you turn up your heating or trigger a hot water demand, this code will automatically change as the boiler fires up.

This status is most frequently seen during the summer months or warmer shoulder seasons when your central heating is turned off and the boiler is only waiting for occasional hot water demands.

DIY fix possible

Check that your room thermostat is turned up higher than the current room temperature.Verify that your heating programmer or timer is set to 'ON'.Ensure the thermostatic radiator valves (TRVs) in your rooms are turned up.

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Related fault codes

All 71 fault codes on the ecoTEC exclusive

Seeing a different code? Every code this model can display, in one place.

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