Chevy & GMC Vans

So I'm driving my 2002 Astro home from Streetside Classics and my check engine light comes on. I got home and checked coolant, Oil level, Air cleaner,looked for leaks and everything was normal-I drove to the gas station to fill up with the check engine light still on. I get to the gas station and discovered my gas cap was not on properly, I fueled up and put the gas cap on securely and after driving a mile the light went off... Go figure.

All obd2 cars check the gas tank pressure to make sure the cap doesn't leak letting fumes out. It became so common for people to bring there new cars back to the dealer with the light on many new cars have a gas cap light seperate from the check engine light. Many dealers were screwing customers over and charging them up to $100 to check the codes instead of just checking the gas cap first.