02 sensor headache
 

I bought an 03 X5 (3.0) about a month ago and the my check engine light is on. Before I bought it, I brought it to Autozone and they said it's an 02 sensor, Bank 2, Sensor 2.

I figured no big deal. Got a new one and now I'm under the vehicle and ...hating my life. Wire to the sensor is cut, but, no big deal. Previous owner probably doing what I would've done. I put a bunch of PB Blaster on it, gave it a few raps with a hammer & screwdriver at the base of it where it threads into exhaust. My 7/8" deep socket isn't deep enough, so I'm using my 02 sensor tool, but, the hex-bolt is stripping/stripped and I can't get a good bit on the sensor. Tried using a propane torch, but, didn't go too nuts; didn't want to overheat anything nearby.

Ofcourse there is no easy access to this sensor. It looks like I may have to take it to a shop and have them drop the exhaust. The bolts look obscenely rusted so I don't like chances of getting them off in my driveway.

Anyone ever wrestled such a beast? Bummin' me out.
Thanks,

Jay

Yep.... I've always had to cut the wire off, then smash the ceramic part of the sensor with a hammer - but this then allows me to use a six point/impact socket plus a 2ft breaker bar on the nut...

Make sure you retap the thread before inserting the new sensor though (I ruined the threads on a new sensor by not doing this first last time I did it...) - an O2 sensor tap is only about £7 for a decent one in the UK...

On the basis that you'll have to go to a shop as it currently stands, then you may aswell give it a go...

Obviously use PB blaster/similar penetrant and as its an exhaust, it can take a fair amount of heat. I am about to change some more and will try using map gas and a blow torch - but the O2 sockets always seem to open up/slip when I use them to remove sensors. Only useful for tightening back up...

Smash the sensor body off and then use a six point socket and a breaker bar...

Yes, dropping is what's needed. Spring of this year we ended doing just as such

Thanks svvg and JSOTO. It's gonna take some work to drop the exhaust so I can even get a work working shot at the 02 sensor. Does no good to complain, but, ...man, it sure seems peculiar that BMW would position Bank 2 Sensor 2 "RIGHT THERE" with virtually no effective access to it. Knowing that they're a bear to get out... (Wanh:dunno:).

Time to start working on those exhaust bolts!!! Thanks all,

Jay

Spray some penetrating oil and deal with it another day. let the kreep oil work....

Bank 2 sensor 2 is the post cat sensor on the left side of the car, isn’t it? Easy access on the n62 4.8... - don't think you need to drop the exhaust???

I have a 3.0 (6 cyl) and the bank 2 sensor 2 is past cat on the passenger side, but, there is next to no room to get in at it. There is a metal bracket bolted into both pipes connecting to the "header pipes" and it is uniquely in the way; not to mention the pipes heading to the rear of the car off the header pipes - they're right in the way of getting at the 02 sensor.

I've got a 2001 3.0i

I just had those O2 sensors out and back in again, still working fine at 186k miles. I took them out as part of my top-end engine rebuild.

I had no problems at all using my O2 socket to get them out and back in (no cutting wires, etc), but this is a CA car. I bought my first car when I was living in Boston, so I know it is a little different out there.

But some info might help:

Those O2 sensors are screwed into a single piece that is the exhaust manifold + cat. If you think getting the O2 sensor out is tough, I promise you getting the exhaust manifold off the head will be tougher. It may have been the single toughest part of the rebuild. So there may not be much benefit to thinking about removing that.

Working back from that point though, it's pretty easy (with no rust). I ended up needing to remove pretty much the entire exhaust except for the driver's side rear muffler. Pretty easy, although it sounds like a lot. I did it to get clearance for removing and carefully reinstalling the exhaust manifolds.

So yes, you might get more working room by removing part of the exhaust from the O2 sensor on back. But don't plan on removing the exhaust manifolds.

I also disconnected the sway bar (roll bar, anti-roll bar, stabilizer bar) links and the sway bar bushings (required removing the stiffening plate) - did all that for just a little extra room to extract and reinstall the exhaust manifolds. Not sure if it will help on the O2 sensors, but was pretty easy for me, and I know sometimes doing a lot of little easy things can make the one really impossible thing possible.

Removing those things should help, as long as removing them is not too difficult.

In case it is not clear, that bracket you mention is just a loose piece held in with the bolts that clamp the exhaust to the exhaust manifolds / cats. So undo those bolts, and the clamp can come right off. Don't forget to put it back on when you're done. You should get a little more maneuvering with that stuff off.

Thanks. Yeah, I have no intention of taking off the exhaust manifolds. I just cant get at the sensor with any room to work and since the previous owner stripped the base of the sensor, I am going to ...need a lot of room to work.