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:
Overview
Center console control panel
VOL: Volume control
MEDIA button
TUNE: Turn to navigate among menu alternatives and folders shown in the
display.
OK/MENU: Press to confirm your selection o ...
Retractable power door mirrors
The mirrors can be retracted for parking/driving in narrow spaces:
1. Press down the L and R buttons at the same time.
2. Release them after approximately one second. The mirrors automatically stop ...
Trailer Stability Assist (TSA)
Trailer Stability Assist is a system designed to
help stabilize a vehicle that is towing a trailer
when the vehicle and trailer have begun to
sway and is part of the Dynamic Stability and
Trac ...
