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:
Glove compartment lighting
The glove compartment lighting switches on/
off automatically when the lid is opened/
closed. ...
Engine compartment
1 Engine compartment, upper
2 Engine compartment, front
3 Engine compartment, lower
Positions
These fuses are all located in the engine compartment
box. Fuses in C are located under A.
NOTE
...
Seat belt maintenance
Check periodically that the seat belts are in
good condition. Use water and a mild detergent
for cleaning. Check seat belt mechanism
function as follows: attach the seat belt and pull
rapidly ...
