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:
Seat belt use during pregnancy
The seat belt should always be worn during
pregnancy. But it is crucial that it be worn in the
correct way. The diagonal section should wrap
over the shoulder then be routed between the
breasts ...
Returning to mode I from mode II
With the remote key fully pressed into the ignition
slot, press START/STOP ENGINE briefly. ...
Information display
Message in the text windows
When a warning light in the instrument panel
comes on, a message is also displayed in the
text window. After you have read the message,
you can erase it by pressing b ...
