Just wondering if anyone has has this problem before. my check engine light is on but when i plug in my code reader it tells me theres no codes. I know there is codes and not just a short or something like that because i had 2 o2 sensor codes and an evap code that have not been fixed yet. also i know the code reader isnt bad because it was able to read the codes on 2 of my buddys jeeps. The reader does get power from the DLC and displays "no codes" when linked NOT no communication. I am simply confused! Any info will be helpful. Thanks!

 

Does using the on-off-on-off-on-off-on key method get you any codes? Depending on your Jeep year it should either blink the check engine or show the codes on the odo.

If this shows codes then maybe the reader has a problem.

 

What year is your Jeep?

 

Its a 98.