O2 Sensor
 

My O2 sensor on 1999 R1100s is not working. Is there any way to replace it without removing the exhaust?

I was able to replace the O2 sensor on my 2004 R1100S without removing the exhaust.
It was some time ago , but I do not think that I had to loosen any part of the exhaust system.
I did have to remove the fairing ( body panel ) because the connect is behind it.

Does there look like there's not a lot of room on the 1999 ?

I was able to get an offset socket onto the sensor but can't rotate it. The regular type O2 socket is too long and bumps into the gear box so I will have to use the offset type. If I could move the collector/catalytic converter (BMW calls it the front silencer) just a little I might have enough room. I'll try to take off the triangular mount on the bottom of the converter and see if that allows it to move enough. Thanks

I used an Open End wrench and a
Crows Foot Wrench.

I've been soaking in PB Blaster so it might come off with an open end or flare nut wrench. Thanks for the reply.

If PB doesn't work try Kroil, I find it to work better freeing up stuck bolts. It penetrates so well it leaks out the top of its own can, so I buy it in spray cans now.