Oxygen Sensors - Post Cat
 

I have a 2001 3.0i. I've tried searching, but can't seem to find how to run the post cat O2 sensor wires from under the car to the top of the engine? Several people have mentioned doing this so I'm hoping I'm missing something obvious.

Also, how did you reconnect the cable holders?

Thanks

You're doing it backwards

1) Take the engine cover off
2) Locate the existing post-cat sensor plug points (they connect to the electricals on the right side of the block)
3) Go underneath the x5 (I did mine on ramps) and locate the post-cat sensors; there are 2 right off the down pipe and cat
4) Tug on one of the sensor cords while having a partner look into the engine bay to figure out which of the two plug points match to which sensor
5) Do one sensor at a time. Unscrew the sensor from the postcat pipe. Remember the cat runs hot and you may need to soak the sensor with liquid wrench before removing. IMPORTANT note how the cable is routed behind the heat shield from the exhaust and into the engine bay. I think there are a couple of plastic holders/snaps which guide the cable. Then unplug the corresponding sensor connect in the engine bay and pull up to remove old sensor
6) Connect the new sensor into the electricals and snake the new sensor down the same path as the old sensor. Remember the heat shield.
7) Spray some anti-sieze / lithium grease on the new sensor threads before screwing in the new sensor.
8) Repeat the process for the other new sensor.
9) Feel good that you've saved 200-300 in labor

Thanks Werewolf,

I already had the engine cover off - I already replaced the pre-cat o2 sensors and spark plugs. Also I have the reinforcing plate off - new to do a couple other things with it off soon.

Overall, the Bentley Manuel I have is good, but sometimes they skip minor details which is why I like this forum - the dyi-ers usually have the details.

About the plastic clips. Did you reconnect the wires to these clips? I can't seem to get my hands in there to loosen, let alone reconnect later. I'm not sure I can see all the clips either - even with a mirror.

Any extra information would be appreciated.

I think the clips are guides (like a series of clothespins) that you push the cables into (on the back of the valve cover and there is one down near the heatshield I think). The same design as the pre-cat sensors

You need to feel them with your hands cuz visibility is zero

GL