The check engine light will illuminate for faults related to smog emissions.
Your car will store dozens and dozens of codes, but only fault codes relating to smog emissions will cause the check engine light to come on, and there are 26 different codes that will cause a check engine light.
All cars had to be OBD-II compliant in 1996, but I think your car became OBD-II compliant in 1994 or 1995. I'm just not sure.
If your car is OBD-II compliant, Auto Zone can read your codes for free.
In any event, there are so many different things it could be that you need to get the codes.
You have the same engine and transmission that are in my car, and common problems that cause a check engine light are:
1. EGR valves / hot inlet pipe plugging up.
2. O2 sensor
3. Transmission upshift delay valve
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".