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:
Spare wheel
The following instructions only apply if you have purchased an accessory temporary
spare wheel for your vehicle. If there is no temporary spare wheel in your vehicle,
please see 284 for instructio ...
Introduction
Information display and controls
1 - READ–press to acknowledge/confirm/ erase a message)
2 - Thumb wheel (used to scroll among the trip computer menus)
3 - RESET–resets certain functions
To scro ...
Periodic maintenance helps minimize emissions
Periodic maintenance will help keep your vehicle
running well. Your Warranty and Service
Records Information booklet provides a comprehensive
periodic maintenance schedule up
to 150,000 miles ...
