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:
Decals
There are various types of decals in the vehicle
whose purpose is to provide important information
in a clear and concise way. The importance
of these decals is explained as follows,
in descending ...
Driving Impressions
Even when equipped with the automatic transmission, the S40 2.4i accelerates
with spirit, though the engine growls when pushed. Despite a taut suspension,
ride comfort is generally satisfactory, b ...
Safety
The S40 has earned good crash-test scores from the Insurance Institute for
Highway Safety. Specifically, it scores Good (the best possible) in frontal and
rear impacts and Acceptable (one ranking ...
