I have a 1994 C280. Since the beginning of this year I have been unable to pull codes from my ODB II code reader. (BTW, the speedometer/odometer stopped working around the same time.) I've tried using other code readers in the port from various places, but they all give me error messages -- none of them will give me any codes. At this point I have to assume there is something wrong with the port internally, or elsewhere on my vehicle. Does anyone have any experience with this? Thanks in advance for your advice.

 

Whatever it is, it doesn't work. It used to work no problem. But now no code reader (mine or anyone else's) works in that port.

 

You should try using your unit on a different car and find out if it is your scanner or a problem with your car. Your 22 year old car may have a issue with a plug somewhere. If so you do have a great clue with what else failed. I hope you have access to a wiring diagram and the knowledge to use it. Good Luck and I hope it is a simple fix Allan

 

It's an issue with the car. As I said above, I've tried several different code readers in my port and none of them work.