I know its obd 1,but how do you get codes for the check engine light?

 

On the passenger side of the engine compartment near the battery attached to the firewall between the battery and the engine is a small 3" x2" approx black box. Lift the cover off and you find a series of led's and one button. with the engine running press the button for 5 seconds release it and the light will start to flash. count the flashes and you have the code. You can google and get what the codes mean and how to reset the codes. search "mercedes E320 Codes"

 

or try http://www.troublecodes.net/MB/