Well, I finally got around to installing my new O2 sensor (P0138/P0139), but I can not get the old freakin' one off! I tried letting the cat get warm and sprayed some PB blaster on, but still no go! I'm afraid of with the cat being so rusted, I do not want to ruin it by trying to get this O2 sensor loose. Any suggestions of how to get this sensor loose? I changed O2 sensors before, but this is the worst difficulty I had trying to change this one. Thanks, any help or suggestions greatly appreciated.

 

what kind of tools are you using? my suggestion is spraying some more PB blaster, let it sit for a little bit.. rent a 02 sensor kit from auto zone... attach that little device to the biggest breaker bar you can fit in there and just force that b*tch out

of course i didn't need tools when i did mine... i twisted my 02 sensor out with my teeth!

 

when i did mine, they were fairly easy to get out.....

 

Liquid wrench worked for me. I tighten it just a little (one good push) then went started at it, took a while but breaker bar helps ( i used the second half of the bar on the lift)

 

Mine was stuck too....

I used a hand held torch...the kind you use to sweat household copper plumbing.
Sprayed the thread area w/ WD40 and then heated the sensor for 30-45 seconds. Used a cresent wrench, of all things, no effort involved to remove, came right out.

 

As previously said use a penetrating oil and an oxygen sensor tool. let it sit over night once you soak it down. Make sure you give it a few good taps once you soak it down. Work the sensor back and forth until it comes free.

 

ummm if it really that hard to take it off .. i say try it with fire .. make it really hot and then use the tool to take it off !

 

Thanks for all your replies. I'll give it a shot by heating it up with a torch.

 

I'm curious as to what kind of wrench (tool) you're using? 1/2" drive ratchet, 3/8" or 1/4"?

 

O2 sensor socket with 3/8" drive ratchet with long extension bars to get more torque in front of car (clearing the bottom of car and ground while the car is jacked up on stands).

 

Is your O2 socket slipping (expanding apart), if the O2 sensor is defective already, cut the wires off and use a 6 pt 1/2" drive deep impact socket with at least a 3ft breaker bar, tighten it a little then loosen it...Good luck!

 

Ive used a 22mm wrench (IIRC). But now i have a Snap on o2 sesnor socket and it works much better.

To the OP try using a 1/2 ratchet..you'll need all the torque you can get. Use as few extensions going to the socket. Get a pipe and put it on the end of the ratchet.

 

that's what I had to do. No sense in using the "special 02 sensor socket" if you're getting rid of the sensor. Cut the wires and do what CMax03 said...

and just use an impact gun. Screw all this breaker bar nonsense

 

I finally got it off. I used a blow torch and heated that sucker super hot. Broke loose like a charm. Looking at the threads on the sensor, it was really seized on there. The next hardest part was threading the sensor in the same route as the old one. How do you even get to those clips to hold the sensor to the chassis of the car? Man, you talk about tight, cramped spaces! What I did was just zip-tied the wire to certain places so that the wire did not lean against any hot spots. Cleared code, and all is good now. Thanks guys for all the help.

 

You might try to chase the threads and reassemble the new O2 sensor with anti-seize ( it's the 11th commandment) Thou shall not use naked fasteners, threads, nor bungs in high temp areas without anti-seize please!!

 

Done that. In fact, I always use anti-seize on everything I replace that deals with any threads.