[dualtjs]

I have a 98 TJ with 114K miles. I need to replace the upstream O2 sensor. I attempted to do so using Eddie's write up on 4X4xploy.com. Given the amount or corrosion on the underside of my TJ, I decided to apply several doses of PB Blaster to the old sensor in the 3-4 days leading up to the attempted removal on Saturday (instructions say this is a no-no, but I knew there was no way that it would come off without, and I'm throwing away the old sensor anyway. In addition, several people have told me that they did so with no problems). I warmed the engine/exhaust pipe to normal operating temps. I still couldn't get the thing out. I stopped when the socket slipped, because I was afraid that I was going to strip the fitting.

One thing that I noticed is that the O2 sensor socket that I bought seems to be too big for the fitting. I expected it to be looser than a normal socket, because it has the open side, but this was more than just a little loose. Using a cresent wrench I measured the size of the fitting and it appears to be 22 mm. The socket is 7/8" (which seems to be very close to 24 mm). Do they make the fittings in 2 different sizes?

[1CleanTJ]

I just used a large adjustable wrench. The correct size open ended wrench would be ideal though. Get the wrench on it and then hit the end of the wrench with your palm/ a hammer/ etc to break the bond and it should spin right off after that.

[bonza]

Originally Posted by dualtjs

IUsing a cresent wrench I measured the size of the fitting and it appears to be 22 mm. The socket is 7/8" (which seems to be very close to 24 mm).

7/8" is just a tad over 22mm.
1" = 25.4mm. 0.875 x 25.4 = 22.225mm
use a caliper to obtain an accurate measurement, so you know what size spanner to use.
a box or open ender is usually better than an adjustable wrench as the jaws tend to spring a little when undoing very tight things and may roll the hex.

[dualtjs]

Thanks guys. I used the adjustable wrench. Cinched it down as tight as I could and applied steady pressure. It finally broke loose.

Now I have to get the *&#^$%^@! new one one. The threaded section of the new Bosch seems to be 1-2 mm larger in diameter than the OE that came off (the sensor end is different and the threading even looks a little different than the OE). I did a search and found others who had similar experiences with the Bosch part. I've got a Denso on order. The fitting looks the same as the OE.

Thanks again.