Vehicles registered in Ada and Canyon Counties and the city of Kuna are required to undergo emissions testing for registration and then every other year.
Diesel Vehicles:
Diesel vehicles are required to be tested in the same manner as gasoline powered vehicles and are provided with the same exemptions.
Exemptions:
1. Motor vehicles with a model year less than five years old.
2. Pre-1981 model year vehicles
3. Electric or hybrid motor vehicles
4. Classic automobiles as defined by Idaho Code
5. Vehicles with a GVWR of less than 1,500 lbs
6. Vehicles with a GVWR of greater than 14,000 lbs
For more information visit: http://www.idahovip.org/
Idaho Code
§ 49-937. Mufflers, prevention of noise
(1) Every motor vehicle shall at all times be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise and annoying smoke, and no person shall use a muffler cut-out, bypass, or similar device upon a motor vehicle on a highway. When any motor vehicle was originally equipped with a noise suppressing system or when any motor vehicle is required by law or regulation of this state or the federal government to have a noise suppressing system, that system shall be maintained in good working order. No person shall disconnect any part of that system except temporarily in order to make repairs, replacements or adjustments, and no person shall modify or alter that system or its operation in any manner, except to conform to the manufacturer's specifications. No person shall knowingly operate and no owner shall knowingly cause or permit to be operated any motor vehicle originally equipped or required by any law or regulation of the state or the federal government to be equipped with a noise suppressing system while any part of that system is disconnected or while that system or its operation is modified or altered in any manner, except to conform to the manufacturer's specifications.
(2) The engine and power mechanism of every motor vehicle shall be so equipped and adjusted as to prevent the escape of excessive fumes or smoke.
(3) No person shall modify the exhaust system of a motor vehicle or a motorcycle in a manner which will amplify or increase the noise of the vehicle or motorcycle above that emitted by the muffler originally installed on the vehicle by the manufacturer.
(4) A showing that the sound made by a passenger motor vehicle or motorcycle exceeds the maximum allowable decibel level shall be prima facie evidence of a violation of subsection (1) of this section.
(5) No person shall sell, offer for sale, or install any noise suppressing system or device which will produce excessive or unusual noise.
Classic
Available for vehicles that are at least 30 years old, do not qualify for "Idaho Old Timer" plates, in original or authentically-restored condition without major modifications from factory specifications, and that will not be used for commercial or regular personal transportation. Only a single rear plate required.
Old Timer
Available for vehicles manufactured before 1943 that are authentic restorations without major modifications from factory specifications and that will not be used for commercial or regular personal transportation. Only a single rear plate required.
Street Rod
Available for vehicles manufactured before 1949, or designed to resemble such vehicles, that have significant drive train updates, such as changes to engine, transmission, rear axle, or suspension components. The body should resemble the manufacturer's original issue. Only a single rear plate required.
YOM
Vehicles manufactured in 1974 or earlier that weigh 26,000 pounds or less may display YOM plates with DMV approval. Use of 1969-73 year plates is prohibited because they did not have the year embossed on them. "Classic" or "Old Timer" plates may be used in conjunction with the YOM plate at the option of the owner. Only a single rear plate required.