The check engine light went on Friday in our 2005 Town and Country. It wasn't the gas cap this time but we found out why the engine light was on before taking it to the dealership.
One commenter on that post suggested getting a CarChip E/X but on the newer models of the Chrysler Town and Country, there's a mechanism to get the codes without taking it to the dealer. I just turned the ignition on and off five times in a row quickly, and the codes appeared in the odometer reading. Then, figuring out the cause from the code was an easy lookup on Google.
The code by itself doesn't tell you what parts need to be replaced, but it does tell you why the check engine light is on. Knowing what got tripped can help lead to more specific information on the web, and give you some talking points if you decide to take the vehicle somewhere to get it fixed.