Downstream o2 sensor

I put on a header and took the jeep down to have new exhaust ran under it. They stripped out the rear o2 sensor not their fault its looks to be in bad shape. So now it is just hanging down under the jeep. Do I really need the rear o2 sensor? It seems to be running fine without it and I am not throwing any codes. They did put in a bung for it if I wanted to replace it.

The rear o2 sensor doesn't control fuel mixture......it's just to test your emissions and to see if your cat is functioning properly. It'd probably throw a code if you didn't have it though. But that's why your vehicle runs fine without it......