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:
Channel lock
Access to specific channels can be restricted (locked). A locked channel will
not provide audio, song titles, or artist information.
NOTE
All channels are initially unlocked.
Locking a chann ...
It's the little things that count
Storage Compartments (Puny, Fair, Ample, Galore): Fair
Cargo/Trunk Space (Puny, Fair, Ample, Galore): Ample ...
