Before an OBD test can be done, most of the emissions control system monitors have to complete their checks of the emissions control equipment. Depending on the age of your vehicle, if one or two monitors have not yet completed their checks, the vehicle is “not ready” for an OBD test. If your vehicle is Unready, you will need to drive your vehicle further to allow these monitors to finish testing the equipment. The amount and type of driving needed varies according to the vehicle.