Hello,

    I was helping a friend replace his O2 sensor in a 99 RX 300. I
had a very difficult time all the way through getting the sensor out
with the little room to move a wrench but I did finally get it out.
When I tried putting in the new one, it would catch on the threads,
but when i put some force on it, it would just pop off again. I am
guessing that the threads are stripped. He did purchase the car used
with 25k miles in 2002. Is it likely that the factory stripped this? I
couldn't imagine that this was replaced at 25k miles. Any input would
be appreciated.

Thanks,
Nick