My car is stuck to the second gear... I had the transmission out drained...

Yes the CHECK ENGINE light is on... Did I use the right ATF fluid? Can my OBD2 machine get the codes?

I have this same exact problem. Except I haven't put any fluid into it and cannot check the codes myself. I bought a 2002 s430 a couple months ago off someone on craigslist and the car seemed amazing when I got it, then a week later the check engine light came on and it drives just.. kinda... like its distraught. it is most evident when its driven on the freeway, which I pretty much will not do knowing It cannot do that. I want to know how much this is going to cost. Did you ever get this problem fixed?

Yes I got mine fixed... the coil was the problem mine was having. I bought new coils for $1700 each and got a mbstar to reprogram the car and everything went fine. Just that the car became as fast as a jet then my kid bro crashed it. I will advice that you check the plugs and coils in yours. It's a V8 engine you have and that should be cheaper to fix compared with the V12 I used to have. Now I have the 2007 S350 and it drives so fine.