On cis-e systems the fuel system computer recorded the check engine info, on 1992 & later EFI fuel systems M.B. used a seperate computer called the diagnostic module that spies on fuel system & accelerator computers.
Most cars w/DM can reset the check engine by cutting the power supply for 10 sec. The 1996 (V8 & V12) & 1997 (4 & 6 cyl) went back to using the fuel computer to record ck eng. info. The codes are different for all of these systems. The only codes that are the same are OBD2.