The float sensor in the tank is stuck or the tank isn't seated correctly.
- First, remove and reinsert the water tank (AS13200250), ensuring it clicks firmly into the base.
- Check the tank's float (the little plastic piece on the bottom). Manually move it up and down to ensure it's not jammed.
- Inspect the tank cavity in the machine. Clean the sensor contacts (where the tank sits) with a dry cotton swab.
If that didn't work, the water volume meter (5213225251) or its connection might be faulty.
Heads up: Use only the original De'Longhi water tank. Third-party tanks may not engage the sensor properly.