I use the ACTRON scanner that they sell at Sears and Autozone and most every other FLAPS. It tells you what code is in, what it means (in a kind of cryptic language - like O2 sensor no activity - for exampls), and it can reset the codes.
For $90 you can buy one. After one use it pays for itself. A 2001 machine should not get too many MIL codes. If you had a 98 or 96, you could surely save money by buying your own scanner.
The other thing to consider is whether or not you would be fixing the problems yourself. Some shops/dealers will not charge for the "diagnostic" if you are going to have them do the repair. Sometimes. If you are planning on doing a lot of your own repair work, then the scanner will come in handy.