Ok hop on over to benzworld dot org and look upp how to make a code reader as the 400E and 500E dont have a built in reader. Use it to check codes, reset the computer, run the car for 30 min varing speed and see if CEL comes on. If it does get codes and repair.

Dont try and cheat, if you remove the light and it doesnt come on it will fail smog for no CEL. I have lived in CA and they are nuts about the CEL. My 93 400E doesnt even have a CEL as it was a dealer option. Its just a set of wires run to the computer to light when codes are stored.