Department of
Environmental Quality

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. In addition, 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, the vehicle emissions testing program was extended to 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 requiring testing must be tested every other year. Even-model year vehicles are tested in even-numbered years; odd-model year vehicles are tested in odd-numbered year. Testing sites are located at small businesses throughout Canyon County and in Kuna. The fee is a maximum of $11 per vehicle test.

Testing Methods

Vehicles are tested for appropriate levels of volatile hydrocarbons (HC), carbon monoxide (CO), and carbon monoxide plus carbon dioxide (CO + CO2). Two methods are used to test gasoline-powered vehicles covered under the program. The type of test required depends on the age of the vehicle.

• Two-Speed Idle (TSI): Samples a vehicle’s exhaust to see if it is above or below certain limits
• On-Board Diagnostic (OBD): Looks for broken or malfunctioning emissions 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.

Visual inspections of fuel systems are conducted on all vehicles inspected. The OBD system is used to check for gas cap leaks on model year 1996 and newer vehicles. Gas caps are tested for leaks on model year 1995 and older gas-powered vehicles.

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 1998 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 revokation of the vehicle's registation. Waivers may be available under certain conditions.