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:
Shiftlock
When your vehicle is parked, the gear selector
is locked in the P (Park) position. To release the
selector from this position, the ignition must be
in mode II (see page 82) or the engine must
...
Defroster
This function defrosts/de-ices
the windshield and front side windows. The indicator light in the defroster button
lights when the function is active.
Blower speed increases automatically and t ...
Security
The Volvo S80 is fitted as standard with a wide range of features designed to
protect occupants from burglary, theft and assault. An electronic immobiliser
makes it impossible to start the car wit ...
