an engine and gas cap symbol pop up on my chrysler pacifica 2007. what do i do?

Have the computer scanned to identify where the problem is coming from. Next, most parts stores will do it for free. Finally, your mileage says 500K which I don't think is correct. The vehicle came with a 5 year or 50K emissions warranty with a 0 deductable. If you are right at or below 50K, it should fall under that if the fuel cap symbol is showing.