91 560SEL Check engine light
 

my car has 140,000 miles. The Ignition coil is starting to go and from time to time, the car will stall or sputter. I have not been driving the car much since there is a little issue with it and I do not want to damage the cats or 02 sensor. Well I have replaced the ignition coil and the car operated great and problem solved. My check engine light is still on though, How do I reset this light on this model? I know there is a diag connector/button on the right side near the battery. Any help would be great

It is an idiot light only for the O2, nothing more.