just bought 2008 S60...check engine light
 

I just bought a 2008 S60 2.5T. It has 100k miles on it.
The check engine light is on. What's the easiest way to diagnose this? Do I need to buy a code checker device, or just take it to Autozone and have them do it?
Where is the plug in?

The plug in is under the dash on the left hand side. Most Autozone's will check it for free. Either way a OBD II reader is a good investment.

Any particular one you recommend?

Any one of these three scan tools will do but I'd go for the Foxwell NT 300 or the T1002 Scan Gauge II.

http://www.ipdusa.com/Universal-Prod...s/c-1-202-627/