We've all been there: you're driving along, minding your own business, when all of a sudden your check engine light comes on or you begin to hear a mysterious rattle that you can't quite identify. At that point, you have two choices: take your car to the repair shop or take the DIY route and figure it out yourself! If you're a DIY enthusiast hoping to troubleshoot an automotive issue before it becomes a major concern, here are 10 car diagnostic tools you shouldn't be without.