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:
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 technician.
...
Driving dynamics: engine
The second-generation, 2.4-litre, five-cylinder, diesel D5 is a cleaner and
more advanced version of the engine fitted to the outgoing XC70. It gives superb
performance (130mph) allied to fuel eco ...
Folding down the rear seat backrests
The rear seat backrests can be folded down for
additional loading space, see page 88. ...
