engine light comes on on 2003 Cadillac Escalade

the engine warning light has been coming on. I took the car to Auto Zone to see what the error was. They were unable to get any reading from their hand held device. Is the only way to get a read out of the problem is to go to a dealer?
This engine light will turn off on its own and while driving pop up.

1 answer
no, you dont need a dealer. take it to a shop and have them check it out for you. they can retrieve the code, do a proper diag and give you a bid for repair.

Roy