It just occurred to me that I do know that Mercedes released in 1993 W124's a pre-OBD-II system, a OBD-I 1/2, if you will.

My 320E has a diagnotic box in the engine compartment, mounted near the battery. It has an LED light, with a button that allows you to activate flash codes. Diagnostic Fault codes that are tripped by systems that affect smog emissions are connected to this LED light. There are several numbered sockets that allow a tech to plug in a computer to scan different systems. Independent techs will frequently use a hand held machine made by a company called "Baum" that allows them to retrieve the codes. Live data can also be retreived via this system. I have been told that nearly all the data that OBD-II stores is available in this sytem.

So, to make a long story short, there is no reason to assume that Mercedes limited this to 1993-1995 W124's. It is just as likely to be available on R129's, possibly several years earlier.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".