Well, I think so

I dived in yesterday. No issues at the battery, just to confirm, but I pulled the lower plate and all the air boxes up top to look over everything well

I haven't found any wiring concerns so far. With searching, it does appear the transfer case oil wear is due to me not able to reset it myself. When I changed it last, I reset apaptations, but it appears only BMW can reset the light.

I did pull all the plugs, and I pulled the pre-cat O2 on back 1 that was throwing the code. I added new plugs and a sensor, and I kept looking for any other possible issues.

I've not found any other problems so I'm putting everything back on this morning so I can do a test drive. I'll drop the oil afterwards when warm, but so far only the plugs looked rough with 70k on them and the O2 definitely looked like it was seeing a rich condition.

Otherwise, my investigation continues