I disagree with Drag79. I have taken my truck to Autozone in the past and had a successful read and solved the problem for around $15. My light came on and the Zone read my code, it just gave them a number, no interpretation, no wizardry, just a simple code that popped up on the scanner.
I then proceeded to do a little search on this site and found out that it was a problem with the throttle position sensor. I ordered a new one the next day and after a 10 minute install, problem solved.
I just don't see the problem with this, if the code turns out to be something beyond your ability, you still aren't out any money. Then you take it to the dealer.
By the way, my truck has been at the dealer for almost a week now, $1200 later, I get it back. Nothing the Zone could do for this one!