Low
S.30 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler is working correctly but is currently in a 'waiting' state because your room thermostat is telling it that the house is already warm enough.

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

Room thermostat is blocking heating mode

From this model's manual
Verified against the Vaillant Ecotec Combi installation & service manual, page 43.
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 status code appears when your boiler is ready to provide heat but is being told to stay off by your external room thermostat or timer. It occurs because the temperature in your home has reached the level set on your thermostat, or the programmer is currently in an 'off' period. Once the room temperature drops or your timer kicks in, the boiler will automatically start up again.

This code is frequently seen during the change of seasons when homeowners first turn their heating on but the outdoor temperature is still mild enough to reach the thermostat setting quickly.

DIY fix possible

Check your room thermostat to see if it is set lower than the current room temperature.Turn up your thermostat to a higher temperature to trigger a heat demand.Check if your thermostat batteries need replacing or if the wireless receiver has lost its connection.

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