codes

I know its asked all the time but a quick search didn't turn up anything, so is there any way to pull codes from a 02 325i? My wife took it by autozone (the closest BMW dealer is over an hour away) to see what was going on with a "service engine soon" light, and he told her it was either the thermostate or thermostate wiring harness. I would like to make sure before I start digging into this thing.
Thanks

codes