The OBD II Diagnostics is actually for efficient engine operation and performance esp
. with the help of chilton auto repair manual. The main objective of efficient operation is for emission control. From the air filter down to the exhaust system there are sensors that provide information to the ECU to control emission. The electronic system of a vehicle is very highly technical that only a diagnostic tool can pinpoint the defective part of engine operation. For those who are interested to learn how diagnostics work, there are many references on the internet as well as in Chevrolet Repair Manual. In learning about it, one will have a better idea when a car is in trouble. The OBD II of cars has standard connecting ports and there are many handheld diagnostic tools available in the market that can be used for any make of vehicle. The tools are reasonably priced and affordable. It will be good to have in the car always.