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:
Symbols in the main instrument panel
Indicator and warning symbols
Other information symbols
Information symbols in the center
console display
Information symbols in the ceiling
console
...
General information
Adjusting the seat belt
Seat belts should always be worn by all occupants of your vehicle. Children should
be properly restrained, using an infant, car, or booster seat determined by age,
weigh ...
Power windows
Driver's door control panel
1 - Switch for disengaging rear door power window buttons
2 - Rear door window controls
3 - Front door window controls.
WARNING
Always remove the ignitio ...
