The check engine light on my 2006 S40 came on the other day. I am thinking of buying my own tester for my car. Can I buy a generic OBD-II tester or do I need some special tester for my car?

 

You can my a generic one, but it will not show you every code that the car can throw. It mainly only tells you the engine codes and some transmission codes. If you want one that will tell you everything, expect to spend some big money.