So I decided to see if my SES light would come on if I plugged the vac port. Car is a 92 L98 formula. Decided to do this since the light does not come on with my 87 L98 bird. SES light came on within the first 15 minutes of driving, so that answers that. Now...after I turned the car off, the light did not come back after I started it again. It came back 2 days later after a pretty decent drive. Turning the car on and off yielded the same things. SES is gone for now. Just disconnected the bat to clear the codes and am wondering if I am on the right track. Will the SES triggered by EGR come on now and again if the codes are not cleared???

 

I dont know if the code will come back more often once its been set once. I dont think so though. The computer runs the check for the EGR once the vehicle is driving at a steady state (cruising) more than 30 MPH. On a MAP car it checks the MAP sensor for a change in vacuum when the EGR is opened.