euro e36 328i engine wiring harness - oxygen sensor placement

[e30austin]

installing an s52 from a '99 M-coupe in a client's '89 325is. the engine harness was said to have come from the same '99 M-coupe, but upon closer inspection, it definitely isn't. this wiring harness is lacking the placement of upstream oxygen sensor connectors - the only ones i have found on this entire harness, are down low, where the secondary oxygen sensors would be, which is irrelevant to me (the DME has been flashed, etc). i'm guessing this is an e36 engine harness, which is okay with me.

my question is: on the euro MS41.1 equipped e36s, since they only had one set of oxygen sensors, where would the placement of those sensors be? i have a feeling the seller of the s52 gave my friend some weirdo euro e36 harness, since those are the only connectors i've found.

the fuel injector rail (where the upstream oxygen sensors would generally be), doesn't have the cutouts where the upstream sensors would be, so there's no way i've missed them somewhere...

thx

[mjweimer]

Could the harness be from an early Z3 2.8 (M52)? Those cars only have one pair of O2 sensors because the manifold downpipes merge into one pipe prior to the cat and out of the cat stays single pipe. You might be familiar with those already...if so just ignore...

[Northern]

Euro E36 came with MS41.0 and only has pre-cat O2 sensors in the headers, 41.0 hardware is different from the 41.1/2 US/CAN versions and lacks all of the internal hardware for post-cat O2, but the ECU pinout is identical besides the 8 disconnected pins.

I'd check the ETM for the X6000 pinout and look at the DME Connector to see which pins are populated