How do you run diagnostics on a car?

Answer by  Amber40 (24961)

It depends on the car. Most cars come equipped with a on-board diagnostic system. It will generate codes on it own that can be read with a scan tool. These tools can sometimes be used to take reading from engine components also.

Answer by  rookie105 (823)

most cars require an external computer to be plugged in to a port in the car and that will allow you to see the error codes