O2 Sensor Stock Sensor Stuck

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FrgMstr

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I have an 08 Vert and am pulling the OE headers, cats, and catbacks off. The downstream O2 sensor was in VERY tight, got about a quarter turn on it and then it seized. Hit is with some penetrating oil, let it sit for a while. Came back and rounded off one side of the bolt face, but finally got it out. The threads in middle of the O2 sensor were destroyed. I am sure the **** is not in much better shape although I have not gotten a peek inside yet.

All stock car, owned by a dealership in MN, so I doubt it has ever been touched according to the service records.

Is this common?
 

ZZ SRT

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Interesting. I just put on high-flow cats and exhaust this last week on my 08 and they came right off with no issue whatsoever.

Did it look like there was corrosion in the surrounding areas where the car had water or salt splashed up? Reason I ask is because if it was from Minnesota, it could have been driven in the late fall, early spring, or even through the winter. I bought a Texas car and it only has 4k miles on it so mine is practically new.
 

Steve M

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Were you using a regular open-end wrench or one specifically for O2 sensors?
 
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FrgMstr

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The other 3 came off without issue. Just got the cat off that had the stuck sensor and the thread inside the **** looks like someone got after it with a chisel. A lot of the threads are missing now. I was not going to reuse it anyway, or the sensor, since I am running Mopar PCM, but I am glad it was not the upstream on the passenger side. I think I would have had to hack the sensor off to remove the the cat through the opening. Got "lucky" I guess.
 
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FrgMstr

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And yes, I was using an open end wrench, hence rounding it off some, but the threads were done anyway.
 

labtec

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02 sensors can be a real problem to remove, I found out the hard way on my twin turbo VR4. There is one underlying cause for this which is the anti-seize compound that is applied to the threads when they are originally installed. If too much is applied, the compound collects at the end threads of the sensor once it is installed. This "extra" compound then gets hard and binds in the threads when the sensor is removed. This is why the sensor starts moving without much effort (wow! that was easy!!) and then after a turn or two starts getting tighter and tighter (oh! "insert your word(s) of choice here"). Trying to break the compound loose by re-tightning and then trying to remove again typically will not work. The sensor threads get jacked (read new sensor) and the pipe threads will need to be re-tapped (buy two taps, you'll need them) also normally by now your "choice" words are being used to create complete sentences. As mentioned above you must use a socket specifically designed for O2 sensors, particularly if they are tight. A regular wrench, even a box type "will" destroy the sensor because of the uneven side pressure applied. This is because the hex area of a sensor is hollow due to the sensor passing through the middle of the hex area. Remember a hardened bolt can help keep a standard nut from deforming however the soft material of the sensor cannot. The nut will deform with a standard wrench easier than you think. This usually occurs about a half second after you mutter the words "just one more turn" and once it does the sensor that was already hard to get out becomes almost impossible.... good luck... your gonna need it:D
 

Timnineside

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My 08 with 60k came out using vice grips lol. Couldn't find a wrench. Also didn't unplug them I just twisted the wires around when I went to reinstall lol. Works great every time!
 

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