How is the OBD test performed?
During the OBD inspection, the inspector will connect a cable to the Diagnostic Link Connector (DLC) located inside your vehicle. The test system will first communicate with the vehicle’s Powertrain Control Module to verify that it has completed all checks of applicable systems and is in a testable state. When the OBD system runs its check on a particular group of components, it signifies this by setting a flag called a Readiness Monitor to Ready or Complete. The more readiness monitors that are Not Ready, the less reliable the results of the OBD scan. For initial inspections, if the vehicle has no more than one readiness monitor Not Ready the OBD test will proceed. If there are 2-3 readiness monitors Not Ready the vehicle will receive a tailpipe test. In any case, 4 or more readiness monitors Not Ready will result in the vehicle being rejected from testing. However, if your vehicle is being re-inspected after previously failing the OBD test, and you have not had repair data submitted
