The world of car diagnostics has changed a lot over the last 50 years. Back in the '70s and earlier, a mechanic's most valuable diagnostic tools were usually their eyes and ears. You could figure out ...

The top end of the technology ladder is held by a scan tool. This car diagnostic tool plugs into the OBD-II port (“OBD” is an acronym for on-board diagnostics, and the “II” designates the second ...