I bought a code reader from AutoTap a couple of years ago. VAG-COM would have been a better investment -- that's what I get for not doing my homework.

What kind of code scanner will work better than the AutoTap for Mercedes?
AutoTap read codes for me several months ago, and now when I really need it (replaced conductor plate - aka turbine speed sensor in tranny) it won't read codes on the car at all. It is monitoring systems -- engine temp, rpm, etc., but won't pull codes. argh! I can hassle them, but they will tell me what they always have -- it's just not made for the German cars.
I'd like your experiences with the different code readers available to the car owner -- not shops -- so I can decide which one to buy after I sell the AutoTap.
Thanks!