O2 sensor conventions?
 

Had all the O2 sensors off for headgasket repair and labeled them all with tape for reinstall. Damn tape came off 3 of 4 in humidity so I’m sorta stuck on which is which. The one labeled is front back of exhaust and has black and grey wires under the insulation. There is another similar, assume it goes rear bank exhaust.

The other pair is yellow and red wires. Assumed these go under the car at the pipe connection.

Right? Wrong? Any way to determine which is which or is it a cable length logic?


Sent from my iPad using Tapatalk

If they are original sensors, each would have a part number that would identify its location. Without being in front of my O2 sensors I wouldn’t know the coloring. There is a reason a standardized location sequence is used in reference to O2 sensor locations. Are you saying the one you have marked is the bank #1, #2 sensor?

O2 sensor conventions?
 

I’m not sure, I marked it simply Rear/Top which in my terms is cylinders 4-6 cylinder head exhaust location. Other would be front /Top being cyl 1-3 head xhaust.

Down below would have been front/bottom, rear bottom. I know technically incorrect but had they not come off would have worked.


Sent from my iPad using Tapatalk

The top sensors are shorter than the bottom ones. 320mm vs 990mm according to RealOEM.

These are the top ones:

http://www.realoem.com/bmw/photos/11781742050

These are the bottom ones:

http://www.realoem.com/bmw/photos/11781433940

Bank #1 is always the bank with the number 1 cylinder in it. The sensors in front or upstream of the converter are labeled #1 & the rears or downstream are number 2. So the sensor of bank #1, sensor #1 would be the front sensor next to the head. Based on what you said & how I interpreted your locations you have the bank #2, #1 sensor. So a similar sensor should be the upstream #1 bank sensor & the other two should both be downstream sensors.

Thanks. I’m on the right track then just need to be sure I’m in the correct banks. I’m likely good up top, at worst have 50/50 chance on getting the bottom correct.


Sent from my iPad using Tapatalk

The part numbers are the same for the two tops. And likewise another part number for the two bottom sensors. So mixing them up front to back should not be an issue as long as you get top and bottom correct.

Thanks. So, is there a specific sensor for each bank up stream and downstream? Or is it as simple as just getting the upstreams upstream and the downstreams downstream.


Sent from my iPad using Tapatalk

^Yep. Just that simple. One part number for upstream (shorter harness) and one part number for downstream (longer harness).

Bank shouldn't matter. There might be small differences I woukd reset fuel adaptations just to wake up the computer.


Sent from my iPhone using Tapatalk Pro