This is a 210 model so it has OBD-II.
I don't think it has an LED like 1995 and older W124's.
It has a better way of retrieving codes, and I think it's through the radio or a/c display.
I know it sounds crazy, but it's in the archives somewhere if you can figure out what to put in for a search.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".