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:
Electrical system
General information
12-volt system with voltage controlled generator.
Single wire system in which the chassis
and engine block are used as conductors,
grounded on the chassis.
Battery
If you ...
Reverse ®)
The vehicle must be stationary when position
R is selected. ...
Safety
Though its sister model, the S40 sedan, earned good crash-test scores from
the Insurance Institute for Highway Safety, the wagon hasn't been crash tested.
Unfortunately, differences in weight and ...
