How do you tell if your car has one? If so, where is the plug located?

 

Most block heaters are on diesels. The plug is usually tucked somewhere on the front bumper.

 

The cord will run one of two places: from under the exhaust manifold to the front of the car or from under the oil pan to the front of the car. If you don't have one but need one, get a proheat oil pan heater. Much easier and probably smarter than a block heater.