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
1 AC – (ON/OFF)
2 Recirculation/Multifilter with sensor
3 Recirculation
4 AUTO
5 Air distribution
6 Passenger compartment temperature sensor
7 Defroster windshield and side windows
8 Rear win ...
On and Off
In certain situations, it may be desirable to switch City Safety™ off, such as
when driving in close quarters where leaves, branches, etc. may obscure the hood
and windshield.
When the engine is ...
Call settings
While a call is in progress, press OK/MENU or the thumb wheel on the steering
wheel keypad to access the following functions:
Mute: mute the infotainment system’s microphone.
Mobile phone: tra ...
