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2001 330i
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3 Posts
Discussion Starter · #1 ·
I got a cel that told me I needed to change the bank 2 sensor 2 oxygen sensor so I went out and bought and OEM replacement part, jacked the car up, and went to work. I tried to use an open ended wrench and one of the special O2 sensor sockets but neither of them worked. The sensor seems to be rusted on and won’t budge. I also tried to use all of the different liquid wrench options as well as 50/50 auto trans fluid and acetone. None of these worked and I am stumped. Is there anyway that I can cut the sensor off and get an impact or a breaker bar on it? Or is there any other options I have to try and take it off? Any advice is massively appreciated.
 

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2,893 Posts
+1 for heater.

When the heater died on the hardest- to- get- to secondary on mine,
I threaded the open end of a 22mm wrench over it, doubled it with a
24mm wrench, and then, flat on my back on the creeper, pushed with
my foot while holding onto the rear subframe.

It cracked loose, but then promptly galled.
An hour of back- and- forth and aluminum cutting fluid later,
it had chowed hell out of the threads in the downpipe.
So, off to Schmucks for the 'rethreading' tool.

If it ever dies again, I suspect it will never come out, as the
rethreader was not kind to the bung.

Heat is far less helpful on the o2, as they're already
pretty thermally tough, AND the same alloys, so they don't
expand differentially like, say, a stuck brake rotor might.

t
lots of swearing.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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5,380 Posts
If you fuck it up (be honest with yourself about your abilities) it will cost you more than a trip to an independent shop.
Proceed methodically.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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5,380 Posts
Now seems a good of a time as any to mention the importance of proper torque for the O2 sensors.
Most factory installed O2 sensors will come out w/o too much fuss, even after very high mileage. With exceptions for rust belt cars.

Just about everyone, technicians included will over tighten O2 sensors. This is where folks run into issues having to remove the 2nd. oxygen sensors someone has installed.

We remove, clean the threads and apply just a small dab more anti-seize lubricant carefully to the threads avoiding getting any on the sensor shield. Then torque to 50 Nm. That's 36 Ft. Lbs.
I know at times it seems as if it's not enough. Trust me it is. There's a crush collar on the bottom, same as on a spark plug. It will hold.
 

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I just went through this... Bank 2 Sensor 2 was stuck and I rounded the nut using those split o2 sockets. I ended up finding a buddy with a oxyacetylene torch. We cut away the metal at the top of the sensor with a saw and broke the porcelain so we could fit a full six point deep 22 mm socket on it. We had to torch it 2 times, heating the area on the pipe where the o2 sensor threads into, the second time it finally popped loose. Take your time, get some heat on it, use a full 6 point deep socket, those o2 sockets spread and strip the nut. Good luck!
927268
 
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