My cel had been on for about 3 weeks when I finally needed an oil change so I had the dealer check it out. Said it was the EGR valve so I had them replace it. The next day, the light was on again. So I take it to the dealer today and they check it out, say that there were some codes that needed to be cleared and it would be ok. Now it's back on AGAIN. This is really frustrating. Since I have already paid for the light to go away (EGR), I'm going to keep taking it back til they get it right. What else could it be ???