I was removing a 02 sensor on a '03 Lexus GS300 and on it's way out it cocked and jamed in the manifold. I didn't realize it was twisted so I kept trying to get it out and long story short, it messed up the thread a little and the new sensor will not go in.

What do I need to do to get this new sensor to start threading in???

 

That's a bummer! Best thing to do would be chase the threads with a tap; don't know the size off top of my head though; do you have a metric thread gauge?

And you'll probably don't have room unless you pull it; yes?

 

Well you could try a thread chaser. Sears sells them, but they call it a "rethreading kit".

If that fails, you could take the car to an exhaust shop and have them install a new bung.

 

The threads should be the same as a spark plug. A spark plug thread chaser should do the trick to straighten them out. Most auto parts stores 4-8 bucks.
18mm X 1.5 is the common size.
If worse comes to worse you can also use a spark plugs heli-coil to repair the hole.

 

Ok, I'm going to go get this O2 sensor thread chaser to see if I can fix it with it. It cost just under $7.
Lisle 12230 - Oxygen Sensor Thread Chaser | O'Reilly Auto Parts

 

How did you manged to do that? I can see how screwing something in and ruining the threads b/c it went in in an angle, but not when backing it out. :?

 

Stupid Lexus. The threaded area is short compared to Volvo, about 1/2. I don't know how really. I was coming out nice and easy then it got hard all the sudden and I seen it looked a little cocked and I gave it a tug and it was pretty much over then. If it was that close to coming out it should have just released but no, turned a 15 minute job into 2 hours.

 

When you're under a car and working upside down, it happens

 

This thing is on top. I think what got me was the O2 ratchet adapter from AutoZone. Put the leverage about 2 inces off center. I got the chaser today and knocked out in about 10 minutes. However, the car doesn't seem to like the sensor. After driving about 25 miles it threw 3 more codes. I told the guy to drive about 400 miles to give the computer a chance to get use to the sensor (bosch) and see what's going on then. I'm going to move this thread to OFF TOPIC.