Protecting Public Health and the Environment.

Treasure Valley Vehicle Emissions Testing

In April 2008, the Idaho Legislature enacted and the Governor signed into law Idaho Code Section 39-116B, entitled the Vehicle Inspection and Maintenance Program, laying the groundwork for requiring vehicle emissions testing in areas of the state where air quality is compromised and motor vehicle emissions constitute one of the top two contributing sources to the pollution. The Treasure Valley airshed meets the criteria specified in the law, as data show that vehicle emissions constitute one of the top two emission sources contributing to ozone concentrations in the valley.

Ada County has had a vehicle emissions testing program in operation since 1984; the program is managed by the Ada County Air Quality Board. In June 2010, vehicle emissions testing became a requirement in Canyon County and the city of Kuna in Ada County. DEQ contracts with SysTech International LLC to operate the program in Canyon County and the city of Kuna. All vehicles subjected to emissions testing must be tested every two years.

Testing Methods

Two types of testing methods are used to test gasoline-powered vehicles covered under the program. The type of test required is determined based on the age of the vehicle.

  • Two-Speed Idle (TSI): Samples a vehicle’s exhaust for appropriate levels of volatile hydrocarbons (HC), carbon monoxide (CO), and carbon monoxide plus carbon dioxide (CO+CO2).
  • On-Board Diagnostic (OBD): Uses an analyzer connected to the vehicle’s powertrain control module (PCM) to look for broken or malfunctioning emission control components. 

Diesel vehicles covered under the program are tested by the OBD method or a snap acceleration test using a smoke meter at the end of the exhaust pipe.

A visual inspection of the emission control components is conducted on all vehicles inspected.

Covered and Exempt Vehicles

These vehicles must be tested:

  • Model year 1981-1995 gas-powered vehicles, using the TSI method
  • Model year 1996 and newer gas–powered vehicles more than five years old, using the OBD method
  • Model year 1981-1997 diesel-powered vehicles, using the snap acceleration method
  • Model year 2008 and newer diesel-powered vehicles more than five years old, using the OBD method

These vehicles do not need to be tested:

  • Electric or hybrid motor vehicles
  • Motor vehicles with a model year less than five years old
  • Motor vehicles with a model year older than 1981
  • Classic automobiles as defined by Idaho Code
  • Motor vehicles with a maximum vehicle gross weight of less than 1,500 pounds
  • Motor vehicles registered as motor homes as defined by Idaho Code
  • Motorized farm equipment
  • Registered motor vehicles engaged solely in the business of agriculture

Failure to obtain a required emissions test may result in revocation of the vehicle's registration. Waivers may be available under certain conditions. Contact the office managing the program in your area for more information.

Staff Contacts

Vehicle I/M Coordinator
Michael Hahn
DEQ Boise Regional Office
1445 N. Orchard St.
Boise, ID 83706
(208) 373-0550

Airshed Manager
David Luft
DEQ Boise Regional Office
1445 N. Orchard St.
Boise, ID 83706
(208) 373-0550

DEQ Resources

Annual Program Reviews

More Information

Ada County Emissions Testing
Air Quality Board
41 S. Baltic Place, Ste. 200
Meridian, ID 83542
(208) 377-9191

Canyon County and Kuna Emissions Testing
SysTech International
1636 East Plaza Loop
Nampa, ID 83687
(208) 468-9710
Toll-free: 1-866-623-8378

Related Page

Vehicle Emissions