Gasoline-powered vehicles:
* For vehicles less than six years old, the tailpipe emission inspection includes a check of the vehicle's emission control system, including the catalytic converter, oxygen sensor, and evaporative emissions control system.
* For vehicles six years old and older, the tailpipe emission inspection includes only a check of the tailpipe emissions.
Diesel-powered vehicles:
* Diesel-powered vehicles with a gross vehicle weight rating (GVWR) of less than 10,000 pounds are subject to opacity testing, which measures the amount of smoke emitted from the exhaust pipe.
* Diesel-powered vehicles with a GVWR of 10,000 pounds or more are subject to a smoke screening test, which visually assesses the amount of smoke emitted from the exhaust pipe.
Exemptions
The following vehicles are exempt from emission requirements in Utah:
- All electric vehicles
- Vehicles over 25 years old
- Any vehicle displaying any state agency special registration plate, including “Antique Vehicles" and Historical Registration
- Vehicles owned by any municipality including state-owned equipment with yellow plates for use exclusively in county or municipal road works
- School buses registered through the State
