Guys! He never said it was a BMW dealer, he just said dealer. This is what he said:

So he was alerted two ways. The sensor is a two step sensor; the first changes the resistance and second is just open. It sounds like it is going to open which is probably why there is no sensor. A previous owner didn't want to pay to diagnose it or they did and didn't want to pay to fix it.

To the OP, you are going to have to check the connector as suggested in post #5 and possible the through the entire path to the module. Look at the connector first.

I bought the car from a non bmw dealer. I think they replaced the pads before the mileage was up on the sensor. I am going to play around with it again in the morning. I bought the sensors off of eBay. I'll take the wheel off again and see if it goes away again. The rotors look fine also. I inspected the pads and they are new. I will post my findings in the morning. Thanks everyone for your help

In iDrive, what does the rears say for mileage until brake service is required?

If less than 50% life left, then that might be the issue. What you might try, take the old sensor from the front, cut the wires and twist them together. Put it on the rear and reset the system again.

Ok went out this morning and the light went off. It must be something loose in the front sensor. I plan on taking it off and putting some grease on the contact points to see if that helps as wheel. The rear pads look good as well.

@ trader I went through the reset procedure through the dashboard and then went into I drive and reset the computer

OE or aftermarket sensor. Some have had issues with some aftermarket sensors in that the pins in the connector break and cause contact issues.

I would seek to find where the bad connection is. I would not band aid it with diaelectric grease. Why does connection fail when tire back on and not when off? Perhaps connection is being pulled when back on ground because the wiring isn't routed correctly. Seek to know what is wrong than fix correctly or pay more later.

This scenario happened to one of my BMW's in the past (can't remember which one). Basically, with new wear sensor, the light stayed on. Lift the car to check things and the light went off. Put the car back on the ground and the light was on. Simple answer was an internal wire break in the wires leading up to the sensor connector. With car on ground, wire would flex to the point of loosing electrical continuity. Raise the car the wire made good contact again. I was able to determine where the internal wire break was located and properly splice the wire back together.

Just food for thought.