What Is the OBD system working correctly? Means:
When the vehicle's ignition switch is turned to the ON position, the "Service Engine Soon" or "Check Engine" warning light should flash briefly, indicating that the OBD system is ready to scan the vehicle for any malfunctions. If there are no problems with the vehicle, the warning light should turn OFF and stay OFF while the key is ON. If the warning light stays ON, the OBD system has detected an emission-related problem.