I have the old style monitor, so I can't comment about the new style. But with mine, the monitor will alert if it loses contact with a sensor, and will beep every time the missing sensor is detected as the monitor rotates through the tires. But it beeps only as long as the missing sensor is displayed, and stops when the monitor moves to the next tire. And it takes an hour for it to alert to a missing sensor. I know this to be true, because of a series of events.
Annoying, but better than being unaware that you have sensors that aren't working correctly.
