What is U18B9 Check Engine Light?

[T_N_C]

2016 x5 40e w/ 65k

Recently did some maintenance 4 plugs (ngk), front diff, tc, rear diff and trans filter/pan and new fluid.

Car drove fine for about a month then I decided to do a transfer case calibration since I replaced the fluid.

Used ISTA for the procedure and everything went good.

Stupid me for messing with it because after that if I accelerate hard I get a drivetrain malfunction warning on the idrive screen and to drive moderately and a check engine light comes on.

I don’t know how to read CEL with ISTA but with regular OBD2 it scans for U18B9?

Googled with some strange results and no real discussions and no search results on here either.

Anyone have experience with this particular code??

[Qsilver7]

When you scan using ISTA...do you get any 6 digit codes that would elude to the car's emissions systems? If you can pull a hex code (6 digits)...try the site below to see if you get anything: https://bmwfault.codes/

What are the Possible Causes of the DTC U18B9?
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

Faulty Module that is not configured
Module harness is open or shorted
Module circuit poor electrical connection

[RED_Y_]

Connect using ISTA and see which modules got errors.