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:
Brake fluid
Location of the brake fluid reservoir
Checking the level
The fluid reservoir is concealed under the
round cover at the rear of the engine compartment.
The round cover must be removed first
be ...
Sensors
The sunlight sensor on the dashboard and passenger
compartment temperature sensor in
the ECC control panel should not be covered
in any way as this could cause incorrect information
to be sent to ...
Compliance
FCC/IC common sentence
This device complies with Part 15 of FCC Rules
and RSS-Gen of IC Rules. Operation is subject
to the following two conditions: (1) this device
may not cause interference, ...
