Low
S.00 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler is working correctly but is currently idle because your thermostat or programmer is not telling it to turn on the heating.

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

Heating mode error – no heat demand

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Pro Ecotec Plus Regular 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 status occurs when the boiler is waiting for a signal from your thermostat or timer to begin heating the radiators. The most common reason is that the room temperature is already higher than the thermostat setting or the programmer is currently in an 'off' period. It essentially means the boiler is sitting in standby mode because it believes no heat is currently required in your home.

This is frequently seen during the transition into Spring or Autumn when warmer outdoor temperatures mean the indoor thermostat is satisfied and doesn't trigger the boiler.

DIY fix possible

Check that your room thermostat is set higher than the current room temperatureEnsure your heating programmer or timer is set to 'ON' or 'AUTO'Replace the batteries in your wireless thermostat if the screen is blank

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Related fault codes

All 101 fault codes on the ecoTEC Pro / ecoTEC Plus

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

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