If you’re not familiar with car Diagnostics, the following may help you understand it a little more.
In modern vehicles, ECUs (Electronic Control Units) are standard equipment. The ECU is basically a computer which can monitor parts of the vehicle as well as change settings in the vehicle. ECUs also have the ability to record faults in their memory which can then be retrieved using the correct diagnostic equipment.
The systems that can be diagnosed depend on the equipment used. For example, using a diagnostic platform that is specific to Volkswagen models will not work on a Honda vehicle or vice-versa. This is because each manufacturer deploys a different communication system. The exception to this is OBD2.
What is OBD2?
OBD2 is an industry standard that is shared by all car manufacturers, but for certain years and engine data only. OBD2 also sets a standard 16-pin connection socket across all cars. This standard was first introduced in the United States via government legislation, then in the European Union (EOBD) and in other parts of the world such as Japan (JOBD), and is nowadays almost universal.
If your vehicle is OBD2 compatible, an OBD2 scan tool can then be used to retrieve basic information on the engine. However, on manufacturer-specific systems e.g. Airbags, ABS, etc; more advanced equipment, experience and training are required in order to carry out diagnosis and repair.