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.
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Quality and Equipment
A passion for high quality lies at the heart of the Volvo brand. This is
inherent not only in the build quality that reflects the ruggedness, durability
and reliability for which Volvo is renowned ...
Unlocking
1. Insert the remote key into the ignition slot
as far as possible.
2. Press the START/STOP ENGINE button.
> A sound will be audible when the lock
releases.
Vehicles with keyless drive*
A r ...
Low beam, Halogen
1. Remove the headlight housing from the
vehicle (see page 322).
2. Remove the cover over the bulbs (see
page 323).
3. Unplug the connector from the bulb.
4. Remove the bulb by pressing the h ...
