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.
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Function
Function overview
1 Visual warning signal, collision risk
2 Radar sensor
3 Camera ...
Approach lighting
Approach lighting is activated by pressing the
approach light button on the remote key (see
the illustration on page 58).
When the function has been activated, the
parking lights, indicator lig ...
Disabling the passenger's side front airbag
Volvo recommends that ALL occupants (adults
and children) shorter than 4 feet 7 inches
(140 cm) be seated in the back seat of any
vehicle with a front passenger side airbag, and
be properly re ...
