I recently purchased a 2007 Jeep Commander Limited with Hemi. On my way home after purchasing the vehicle, I decided I needed more gas so I stopped by the closest station to fill her up. A few minutes later my check engine light lit up and I panicked. I tried calling the seller, but he could not be reached. My phone's battery also died, so I decided to drive home slowly and went straight to a Jeep dealership. Basically the mechanic told me something that I should have known from past experience, my gas cap was loose because my mind was someplace else wondering about what lift I was going to buy, mud tires or all terrain and if I needed wheel spacers..hence the check engine light. I learned two things today, we are too dependent on our phones and technology, it was my first time in a long time to not use a GPS to get home (100 miles), turns out there are signs everywhere for us humans to see and follow. Lastly, living in a state that requires full service gas stations has it perks for day dreamers like me. Thanks for all the info shared!