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:
Tire Pressure Monitoring System (TPMS)
The tire pressure monitoring system1 uses sensors
mounted in the tire valves to check inflation
pressure levels. When the vehicle is moving
at a speed of approximately 20 mph
(30 km/h) or faster, ...
Power seat
Operation
Driver's seat: The seat can be adjusted if the
ignition key is in position I, II or if the engine is
running. It can also be adjusted as follows with
the ignition off:
• Within severa ...
Under the Hood
A 2.4-liter inline-five-cylinder produces 168 horsepower in the base wagon.
The high-performance T5 holds a turbocharged 2.5-liter five-cylinder that
generates 218 hp and 236 pounds-feet of torque ...
