Chrysler Town and Country check engine light

had check engine light come on continuously with a code that stated i had a small leak somewhere. no specific ID. Checked everything but after about 50-100 miles same thing would happen. Purchased a new gas cap because old one had a small crack on rubber seal. Didn;t work. Finally, I purchased an ORIGINAL gas cap from chrysler and the problem was fixed. Common auto part store gas caps are not made specifically for your car, they are universal caps made to fit many cars. A small difference here will cause a failure to show up on the check engine system. After few thousand miles all is A-OK