Review on Autel MS309 Universal OBD2 Scanner: Engine Fault Code Reader for Clearing Codes, Viewing Freeze Frame Data, and Completing I/M Readiness Smog Check by Joe Medlin

It couldn't be simpler. Received the device, quickly read the instructions. Popped it into my GMC and hit enter three times and code PO446 (exhaust emissions) came up. Considering I've seen this code before, when I asked the store to pull the code I knew it was related to a faulty gas cap or similar item. Although you can delete the codes by disconnecting the car battery, the device has a delete function. Just go back to the main menu and click on the items to go to option 2, Delete. Confirmed by pressing the enter button again and the code was cleared and the check engine light went out.