You can go on Amazon and buy a OBD scanner like this one
http://www.amazon.com/Autel-MaxiScan...s=odb2+scanner
It will plug in under the steering wheel and spit random codes out on a screen indicating there is a problem in the car or not. A good cheap tool to have anyway. You will have to look the codes up (if any appear) once you get them from the scanner.
Useful, but more so for other cars and not my Z.