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:
Steering wheel keypad
The keypad varies according to the vehicle's equipment
1 Turn the thumb wheel to go up/down
among menu selections. Press the thumb
wheel to make a selection or store a function
in the system' ...
Belt check
Check the belt regularly to make sure it is in
good condition and is clean. A worn or dirty belt
can cause poor cooling and low alternator output
as well as impair the operation of the power
steer ...
Introduction
Air conditioning
The vehicle is equipped with Electronic Climate Control (ECC). The climate control
system cools, heats or dehumidifies the air in the passenger compartment.
NOTE
The air ...
