So, what do you experts make of this piece of ...!
 

After a lot of struggling under the car, this is what finally came out of my 'S'-pipe! Lovely, eh? Needless to say, it doesn't thread into my CEL Eliminator and the Eliminator doesn't thread into the bung :flame:.

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Hope you guys don't mind if I'm having unkind thoughts towards Toyota at the moment :flame:!

Those things are in there hella tight, I know I had problems with mine. Take it to an exhaust shop and get a new one welded on, they'll probably charge like $20

The only explanation that makes sense to me is it was originally cross-threaded at the factory.

I presume you're talking about replacing the 'S'-pipe bung? I'm wondering if I can run a die over that wasted sensor thread and get it good enough to use, and perhaps a tap would recover the bung. Course, I don't yet know what thread size it needs :(!

That's some hella JDM loctite.

*like* lol

Dang. I ended up buying a set of sockets JUST for 02 sensors after trying for 15 minutes to get it off.

I used both the correct slotted hardened tool for the job and (mostly) a 22mm combination wrench direct to its base. I fought it and it fought me for a considerable period of time and effort (way more than fifteen minutes). Unfortunately, the above photo depicts my reward :(!

it happens. some o2s do this and some dont the colder the exhaust system is the better chance of the o2 not doing this.

The exhaust system couldn't have been colder, the engine hadn't been run for 18+ hours. The front O2 sensor was perfectly reasonable, this one wasn't -- I have a hard time viewing this as anything other that an original Toyota screw-up.

DANG.

Sorry to hear it man....

And I'm sure it was but Toyota probably wont replace it same thing happened to me and I ended up just buying a new o2.

No question, I've no doubt I've no recourse, but it's a huge ____er none-the-less :flame:! And I should let their dealer "technicians" touch my car? FY Toyota!

yeah same reason why i do everything myself good luck man

OK! By grinding the destroyed thread and filing the entry to the remaining thread, I'm now able to cleanly install the sensor into the Eliminator. Can someone please tell me what tap size I need to restore the O2 bung thread?

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From hunting around on the net, it appears as though the correct thread spec is 18mmX1.5. It also appears the O2 bungs are normally much harder than the sensor threads and so a chaser may well be sufficient to clear it. However, since I can't even start the Eliminator into the bung, it seems unlikely I'd have any better luck with a chaser :(!

Hit it with a torch, then try tapping it? (not sure if you have access to a heat source or not, a local exhaust shop would probably do it)

Picked up a chaser today and spent some quality time (???) with the 'S'-pipe trying to remove it from the car. After soaking the rear bolts with solvent, I was finally able to break them free with a breaker bar and took the following photos of the bung threads.

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Looks to me pretty much like metal was poured over them :(! Tried the chaser a little, but all I was doing was hurting the chaser threads. Just ordered a tap and so the car will remain dead for a few days -- thanks Toyota :flame:!

Finally, back to where I should have been Sunday! Though, I hadn't really expected to have to remove the 'S'-pipe.

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Bummer! I fought with mine too but in comparision mine was a cake walk. In case it helps anyone else, I soaked mine with PB Blaster and then used MAPP gas to heat and expand the s-pipe bung and a "good" closed end wrench on the O2 sensor. Mine finally broke free with all threads intact. Be sure to use a good anti-sieze compound on the threads of all O2 sensors on re-installation.

Of course, YMMV.

I used anti-seize on the front sensor, Eliminator, and 'S'-Pipe to scuba bolts, but I had to reach up above the pipe and Eliminator to install the rear sensor and chances were too great my fingers would contact both the compound and the sensor tip -- really poor accessability while lying on my back under there. I tried orienting the Eliminator forward, but then the sensor cable was too short -- if I have to remove it in the future, I'll probably be glad it only has three threads since it won't be able to fight as hard :)!

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I'm quite certain it was cross-threaded, the three surviving threads were mostly protruding from the bung when I started, and the crushable washer wasn't tight. It was a couple or more orders of magnitude harder to turn than the front sensor.