I replaced the entire exhaust on my 85 GSl - 12A today from the manifold back. The cats were shot and the previous owner had removed all the flanges and welded everything together.

I am not running a cat on this exhaust system. I had to cut a sensor off the old intermediate pipe as the bolts were rusted on.

the new intermediate pipe has a provision for the sensor. What is this sensor for and what will it affect if I don't reconnect it?

any advice is appreciated