I bought the universal code reader from Harbor freight ($39.99), item # 46030. I tried reading a check engine situation on a 1996 SL320. It was unable to pull the code. Then i tried with an Actron 9135 and it read the error code (P0441). Harbor Freight tech support told me that their reader can only read universal or generic OBDII. Not sure why the Actron (non proprietary) would work but not the HF one.

I am looking into the Actron CP9145 which also allows reading live streaming data. I might buy that one.

__________________
1972 450SL
1982 300D Turbo