Emissions Testing in Idaho

Testing Requirements

Current Testing Requirements in Idaho

Idaho has no active emissions testing requirements. The legislature repealed the state mandate in 2022, and testing ended on July 1, 2023, in Canyon County and the City of Kuna. Ada County's program also ended in 2023 after EPA approved the removal of the federal requirement. The Idaho Department of Environmental Quality confirms that all I/M programs in the state have been suspended. Vehicle registration and renewal through the Idaho Transportation Department do not include any emissions component.

Who Needs an Emissions Test or Smog Check

No vehicles in Idaho are required to pass an emissions test. The state does not enforce smog check requirements for gasoline, diesel, hybrid, or electric vehicles. There are no model year restrictions, weight limits, or fuel type requirements that trigger testing. This applies to all counties across the state, including Ada and Canyon counties where testing was formerly required.

How Often Tests Are Required

There is no mandated testing frequency in Idaho because the state no longer requires emissions inspections. When the Ada and Canyon county programs were active, affected vehicles were tested every two years. That biennial schedule no longer applies. No testing schedule is tied to registration renewal.

Where Emissions Testing Is Required

No areas in Idaho require emissions testing. Ada County and Canyon County, including the City of Kuna, formerly operated programs as part of the Treasure Valley Airshed nonattainment area. Both programs ended on July 1, 2023. All other Idaho counties never had testing requirements. The entire state now operates under the same policy of no mandatory emissions testing.

What Happens During the Test

Idaho does not require emissions testing, so there is no active test procedure to describe. When the programs were operational, vehicles from model year 1996 and newer received an OBD-II diagnostic scan. Technicians checked readiness monitors, diagnostic trouble codes, and the malfunction indicator lamp. Vehicles from model years 1981 through 1995 received a tailpipe test. Vehicles from 1976 through 1980 received a single idle speed test. A gas cap pressure check was performed on all vehicles. A lit check engine light resulted in automatic failure. These procedures are no longer required anywhere in the state.

Areas in Idaho That Require Emissions Testing

No areas in Idaho require emissions testing. Cities such as Boise, Nampa, Caldwell, Meridian, Eagle, Star, Kuna, Garden City, and other Treasure Valley communities were formerly covered by the program. Cities outside the Treasure Valley, including Idaho Falls, Pocatello, Twin Falls, Coeur d'Alene, Lewiston, Moscow, and Rexburg, never had testing requirements. The state does not maintain a list of emissions testing stations because no mandatory program exists.

How the Emissions Test Works in Idaho

Idaho does not have an emissions testing process because no program exists. Drivers do not need to visit any station or submit test results for registration or renewal. When the programs were active, drivers visited state-certified testing stations, often recognizable as red vans parked at various locations throughout the Treasure Valley. The test took approximately 15 minutes. If a vehicle failed, the owner had 30 days to complete repairs and return for a free retest. A waiver was available if the owner spent a minimum amount on qualifying repairs and the vehicle still could not pass. Today, none of these procedures apply.