How do states use OBD II for emission inspections?

Many states connect a computer directly to a vehicle's OBD II system. The inspector can then read "faults." In some states, this type of inspection has replaced the tailpipe emission test.
See also:
Steep inclines and/or heavy loads
ACC is primarily intended for use on fairly level roads. The system may have
difficulty maintaining the correct distance to a vehicle ahead on steep inclines,
if the vehicle is carrying a heavy lo ...
Exterior
For 2008, the nose and tail are modified, and though Volvo says it has
changed the headlights and taillights, it seems limited to the elements within,
such as taillamp LEDs and lens colors, and no ...
How BLIS functions in daylight and darkness
Daylight
BLIS reacts to the shape of surrounding vehicles. The system is designed to help
detect motor vehicles such as cars, trucks, buses, motorcycles, etc.
Darkness
BLIS reacts to the headligh ...
