I have not driven my RT in 3 weeks. It has no mods. I started it up this morning and let it idle for about 15 minutes. When I got in the car I noticed the check engine light was on. I did replace the gas caps with a lock gas cap about 2 months ago. So I decided to put the factor gas cap back on. The engine still stays on. I drove it on the beltway 50 miles and the light is still on. It drives and rides just great. It just passed state emissions 4 weeks ago. I am thinking maybe I put some bad gas in it. Sometimes I go to these discount gas stations to fill up. Does anyone have any suggestions before I take it to my Viper tech?