[infinitigor]

I currently have some 3inch downpipes on the car, and will be replacing them with the stock cats tomorrow.

My main worry is making sure the 02 sensors are placed into the right place so no codes get thrown.

I am returning the car for a lease and definitely cant bring them a car with 02 sensor check engine codes, and then have BMW find out the sensors are in the wrong places.

I believe there are rear and front 02s, is there a way to tell and not make a costly mistake ?

[iBoost]

Place a tape and write numbers on them and remove when all done

[robc1976]

Originally Posted by infinitigor

I currently have some 3inch downpipes on the car, and will be replacing them with the stock cats tomorrow.

My main worry is making sure the 02 sensors are placed into the right place so no codes get thrown.

I am returning the car for a lease and definitely cant bring them a car with 02 sensor check engine codes, and then have BMW find out the sensors are in the wrong places.

I believe there are rear and front 02s, is there a way to tell and not make a costly mistake ?

you can't put the rear in the front but you can mix the rear and front O2's on front and back.

Front DP O2 = black wire (coating)

Rear DP O2 =grey wire (coating)

[USAF Rick]

There are two O2 sensors in the front, and 2 towards the back. It shouldn't be confusing getting the fronts and backs mixed up because of it's location. If you watch the AR DP install video, they did a good job explaining that the O2 wiring with the gray sheath goes to the shorter DP which goes to the rear turbo, and the black sheath goes to the longer DP which is for the front turbos.

Here's the video:

At about 2:45 in the video is when they start taking apart the O2 wires. But I agree with iBoost, tape the wires and mark them so you'll have less chance of mixing it. Good luck, have fun!

[infinitigor]

thanks guys, very helpful information

this is a MUST know! it would be so annoying to have to get under the car again to fix this a 2nd time