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Thread: Oxygen sensor removal

  1. #1
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    Oxygen sensor removal

    Does anyone have any tips on removing the o2 sensor on the m30? Been trying for a a day now and it's not breaking loose. Using a offset o2 socket the whole time while drowning it in penetrating oil. At this point, I might drop the exhaust to have it done. Any tips are welcome!

  2. #2
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    We used one of these and they work. Twelve bucks BavAuto. Just type in O2 sensor tool. You don't have to drop the exhaust. You can reach on top of the Cat to get to it.

    Last edited by CroughtonE32; 04-23-2017 at 10:55 PM.
    1990 735I (Auto) E32 Feb 1990 to Present
    1996 Z3 Roadster (5 Speed) E36/7 Jan 1999 to Dec 1999
    1983 733I (5 Speed) E23 April 1983 to Feb 1990
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  3. #3
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    Did you get it from the top? I've tried turning it from the passenger side and from the bottom where the cat splits. Can't really get anything to fit from the top. I have one just like that put I think I need to get a thinner one since mine is much more bulky. I don't know what was done but sensor in there now buts a little crushed at the top. I knew it was gonna be a PIA to remove but this is crap. Will update in a day or two.

  4. #4
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    I should do mine it looks original. It may be part of my rough idle. I just dread trying to get it to break loose.

  5. #5
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    On the 750 we use just a normal long wrench , as shown here http://infinitier.ddo.jp/e32/page/ma...inte_50707.htm
    we just remove the brackets from the exhaust in the rear and the middle and then the exhaust drops a bit down (I use a scissor jack underneath the rear muffler and can nicely move it up and down), that is enough that you have access to the O2 sensor.
    In case the sensor is stuck, we cut the wires off at the top of the sensor and use a ring wrench, that has more grip, tightening the new one with open wrench.
    Shogun tricks and tips for the E32 series are HERE!

  6. #6
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    Quote Originally Posted by shogun View Post
    On the 750 we use just a normal long wrench , as shown here http://infinitier.ddo.jp/e32/page/ma...inte_50707.htm
    we just remove the brackets from the exhaust in the rear and the middle and then the exhaust drops a bit down (I use a scissor jack underneath the rear muffler and can nicely move it up and down), that is enough that you have access to the O2 sensor.
    In case the sensor is stuck, we cut the wires off at the top of the sensor and use a ring wrench, that has more grip, tightening the new one with open wrench.
    I'm going to give it one more go then I'm just going to cut the wires and remove it like that. Not helping that I think I'm starting to round off the bottom. I've been holding off doing that just in case I need to drive a long distance. I'ts coming off this week!


    I think mine is original too. It's a huge pain if it's never been removed. My skinned knuckles can attest to that! All I would have to say is drown it in penetrating oil days before!

    Quote Originally Posted by TonyPa View Post
    I should do mine it looks original. It may be part of my rough idle. I just dread trying to get it to break loose.

  7. #7
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    Okay, I'm at a loss here guys. Looks as if the sensor wasn't tightened all the way to the base so there was space between the two. Now it's as if they have fused together over time. Been working on this for four days and I've gotten nowhere. What should I do here? Would a torch help?
    20170424_210942.jpg 20170425_110236.jpg20170424_210927.jpg
    Last edited by NE32; 04-25-2017 at 08:40 PM.

  8. #8
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    Here are some comments on the same problem https://www.bobistheoilguy.com/forum...&Number=795633
    Shogun tricks and tips for the E32 series are HERE!

  9. #9
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    this may sound stupid, but would it help if you ran the car for a little bit and let the catalytic converter get really hot. The same effects of heating it up?

  10. #10
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    That is mentioned in my link too:" let the car warm up before you try to remove the O2 sensor"
    Shogun tricks and tips for the E32 series are HERE!

  11. #11
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    I didn't check the link yet, was just a quick reponse. I see Bosch O2's on ebay. Universal ones. Not sure if their ant good but their much cheaper.

  12. #12
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    Universal ones are without plug, the come with special crimps. I prefer cpl. one with wire and plug. Better buy a fitting one with the proper plug. Bosch, Denso, NTK and no name with wire and fitting round plug. nEbay you get a Bosch for abt. $75, and no name Made in China from Hongkong or even the U.S, for $25 +
    Shogun tricks and tips for the E32 series are HERE!

  13. #13
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    I have always bought oem stuff for my baby. I just figured I would bring it up just in case it was a good deal. I do prefer factory oem, just makes me feel better.

  14. #14
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    Heat and penetrant. ATF & acetone mixed 50/50 makes the best penetrant, better than PB Blaster. You must heat the weld boss to almost a cherry red with a torch, being careful to wipe off excess penetrant beforehand and anticipate more flareups. Whack the wrench with a mallet. Lisle makes an impact attachment for an air chisel, p/n 43960, which works exceptionally well.

    I have had no problems with the universal 4-wire spliced sensors.
    Last edited by TheStigg; 04-27-2017 at 02:23 PM. Reason: (corrected part number)
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  15. #15
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    A little update....haven't bought a torch yet. Never really used one before so I wanted to exhaust all my options before going that route. What I have been doing is using the Acetone/ATF mix and chiseling between the senosr and the cat base with a screwdriver and hammer. It has worked TREMENDOUSLY. Only problem is trying to get the top of the senor since it's awkward to get the scewdriver in there but it'll work. Letting the mixture soak in for a day then giving it another try.

  16. #16
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    Alright, FINALLY got it off. Definitely the original sensor. Took a total of 10 days to get it off. Just need to do the magic reset and I should be good to go!

    20170502_120055.jpg20170502_120107.jpg

  17. #17
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    O2 sensor hell, you pretty much went through what I did. In fact, putting in new ones I think resulted in one being cross-threaded. The car has slight issues such as startup stumble when shifting into reverse or drive. So a bit later on, I took it to an exhaust shop to have two new sensor bungs installed just below the factory one. Basically at a 90 degree. Then I put in two new BOSCH sensors, not Denso. Every since then the car has run just fine. Its even possible that due to cross-threading one of the sensors cracked, they are ceramic inside and a touch fragile. The good thing is that if I have to replace them again, they will be much easier to get it! Also I never did remove the old ones, they still sit there.
    ______________________________
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  18. #18
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    I was going to do the same thing! lol I told myself if I couldn't get it this week then I'm taking it to a shop and having them weld in a new bung and leave the old in. Glad I wasn't the only one who thought about that lol

    Quote Originally Posted by unity View Post
    O2 sensor hell, you pretty much went through what I did. In fact, putting in new ones I think resulted in one being cross-threaded. The car has slight issues such as startup stumble when shifting into reverse or drive. So a bit later on, I took it to an exhaust shop to have two new sensor bungs installed just below the factory one. Basically at a 90 degree. Then I put in two new BOSCH sensors, not Denso. Every since then the car has run just fine. Its even possible that due to cross-threading one of the sensors cracked, they are ceramic inside and a touch fragile. The good thing is that if I have to replace them again, they will be much easier to get it! Also I never did remove the old ones, they still sit there.

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