On my 98 Grand Cherokee 4.0L I am having problems getting the downstream O2 sensor out to replace (the one that goes into the catalytic converter ). I have to tool to get it out and i soaked the sensor with WD-40 to try and get it to bust loose. This thing will not budge. It is almost like the 7/8 O2 sensor ratchet will not sit flush on the sensor. So I tried the 22mm and it STILL will not sit flush. Is there any trick to getting this sensor out that you guys might know about? I am away at college and the only other thing I can think of is to put heat on it with a torch but I do not have access to one up in the mountains at Penn State. Any help would be great. Thanks.

Did you try a box end wrench? Try to wire brush it to get all of the road crap off of it then soak it and try again.

I would use a wrench instead of the 02S Sockets. and soke it with PB BLASTER and then use some heat a bernzomatic propane torch is good in this situation.

heat does wonders!

got it out with a cheap propane torch from lowes. but wow it took a while to get that bad boy out. i got to get my acetylene torch up here haha.