My check engine light is on but Auto zone said my Cadillac converted is going out

They sell parts,they want you to buy a new OEM converter for your car because their score board will look better! Autozone for starters does NOT have the proper equipment to test for that but they want you and try and convince you that is what is wrong,NOT TRUE! Probably what happened is your check engine light came on and they read the code with an OBDll code reader,then they put that code # in their computer,then computer prints out a list of possible causes and that only means it gives you a starting point and not to go throwing money and parts at your vehicle.I would find a local,trusted,independent repair shop with a good mechanic with a real scan tool before doing anything to it! Autozone will tell you anything to get you to buy parts that you don't need! Most that work at AZ don't know the difference between a Muffler and a Catalytic Converter until they look it up on their computer,then they only know what it looks like!