Hello! I recently purchased a used 2006 Dodge Grand Caravan (VIN 1D4GP45RX6B528573) with 186k miles on it from a private seller here in Virginia. I bought it for $900 and it seems to drive decently. However, the seller told me that he let the car sit for 2 years and only occasionally drove it. The biggest concern aside from the other things with it is that the CEL will not come on at all when I start the car. It has rendered the car unable to pass emissions (which is needed first in this state before receiving registration), and it has apparently been rejected before. I took it to Advance Auto Parts for a scan and it came back saying something about Emissions Related Engine DTCs (I’ll attach photo to this). I also took it to two different repair shops where it failed the pre-test and the only thing one of the mechanics could advise me was to drive the car for “a while” but unsure how long or far that is supposed to be. Transmission and engine don’t have any immediate visible issues. What could be the culprit in this situation? Thank you for any feedback. 

p.s. Not sure why, but I can’t attach the photo of the reading. It states: “No Powertrain DTCs of Freeze Frame data is presently stored in the vehicle’s computer.”