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:
Interior Air Quality System (IAQS)
A multifilter helps reduce gases and particles
in the incoming air, thereby reducing the levels
of odors and contaminants entering the vehicle.
The air quality sensor detects increased
levels o ...
Generator warning light
If the light comes on while the
engine is running, have the charging
system checked. ...
External sound sources
USB flash drive
To simplify the use of a USB flash drive, it is
advisable to only store music files on the drive.
It will take considerably longer for the system to index the files on the drive
...
