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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Introduction
The HomeLink Wireless Control System provides
a convenient way to replace up to three
hand-held radio-frequency (RF) transmitters
used to activate devices such as gate operators,
garage door ...
Accessory installation
We strongly recommend that Volvo owners install only genuine, Volvo-approved
accessories, and that accessory installations be performed only by a trained
and qualified Volvo service technicia ...
Driving on rough/unpaved surfaces
The Volvo XC90 is designed primarily for onroad
driving, and it has excellent handling characteristics
on very rough or unpaved roads.
When driving on poorly maintained or unpaved
roads, please ...
