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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Modifications
If you are considering modifying your vehicle in any way to accommodate a disability,
for example by altering or adapting the driver's or front passenger's seat(s) and/or
airbag systems, p ...
Cleaning the sensors
Park assist sensors
The sensors must be cleaned regularly to
ensure that they work properly. Clean them
with water and a suitable car washing detergent.
Ice and snow covering the sensors may c ...
