I am trying to get old O2 sensor out. It won't budge. I am using O2 sensor socket. It seems to be starting to round off the sensor. Any tricks or ideas??
Joe

 

have you tried to run the car for a few min's before trying to remove them? This will allow the pipe to expand prior to removal.Be sure to turn the car off before trying to remove it.

 

Dab the base of the sensor with a little penetrating oil. Start the engine and allow the catalyst to warm up a little.

Then shut the engine off. It's easier to remove the sensor if it's warmed up when they balk like that.

 

If you plan on replacing the old O2 sensor, you could clip the wire lead from it and just use a deep 6 point socket (unless the O2 socket is already a 6 point, in which case that advice probably won't help you).

You can also soak the visible threads with penetrating oil (and let it sit overnight) or apply some heat from a torch to the O2 bung on your exhaust pipe, then give the 6 point socket another try.

If the edges have gotten to point where a 6 point socket is slipping around them, it might be time for vise grips (and more heat).

Good luck!