Hi,

You say you don’t get codes?
Are you getting any blinking red light from the little box?
I ask as there might be corrosion someplace.

The CEL and the Service light are two separate animals.
The CEL is for emissions purposes and the Services is an oil change reminder.
I think it might trip on every 7,500 miles but I’m not sure. It is resettable from a peg on the face of the instrument cluster’s bottom right hand corner.

As I remember the # 6 socket is a test socket to operate various components a visual or hearing test. I haven’t had to mess with my diagnostic port in a long time.

If the EGR doesn’t respond with a temperature change, in the down pipe or body, after a set time, the ECU trips the light on!
The car runs fine, it’s the eyeballs that get strained and then, the brains! (:-)

I have had this EGR code twice on my 1991 and each time it’s been the controller valve to the EGR getting a plugged up exhaust or intake equalization vent under its little gray cap!
Originally it had a foam rubber that rotted. I replace it with a polyester fabric stuffing piece.
This is located on the left side strut tower.

I hope some more BB subscribers chime in as I’m not that keen about what causes no codes.

Phil