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:
Rain sensor
The rain sensor automatically regulates wiper
speed according to the amount of water on the
windshield. The sensitivity of the rain sensor
can be adjusted moving the thumb wheel up (the wipers w ...
DSTC system
The Dynamic Stability and
Traction
Control system (DSTC) ...
Limitations
Even if a fairly small section of the screen image
appears to be obstructed, this may mean that
a relatively large area behind the vehicle is hidden
and objects there may not be detected
until ...
