Modern vehicles have an OBD - On Board Diagnostic Interface, a standard interface for vehicle electronics, about the error and status messages can retrieve from the control units. With suitably programmed microcontrollers can be relatively easy to build an interface to query with their own laptop or PC these messages. There are also a number of programs on the Internet, for example, OBD Diag

Here you may find Circuit, Basics, Schematic Diagram and DIY Kit components for OBD OBD2