1. (1) A person shall not knowingly disconnect, deactivate, or otherwise render inoperable a motor vehicle's emissions control system that has been installed by the manufacturer of any automobile of a model year of 1968 or later, except to repair or replace a part or all of the system.
2. (2) A person shall not operate on a highway an automobile described in subsection (1) of this section knowing that the emissions control system installed on the automobile has been disconnected, deactivated, or rendered inoperable.

3. (3)

   1. (a) A person who violates subsection (1) or (2) of this section commits a class A traffic infraction and shall be fined thirty-five dollars pursuant to section 42-4-1701 (4)(a)(I)(N). The department shall not assess any points under section 42-2-127 for a conviction pursuant to subsection (1) or (2) of this section.
   2. (b) A person who violates subsection (6) of this section commits a class A traffic infraction and shall be fined one hundred dollars pursuant to section 42-4-1701 (4)(a)(I)(N). The department shall not assess any points under section 42-2-127 for a conviction pursuant to subsection (6) of this section.
4. (4) The air quality control commission may adopt rules and regulations pursuant to sections 25-7-109 and 25-7-110, C.R.S., which permit or allow for the alteration, modification, or disconnection of manufacturer-installed air pollution control systems or manufacturer tuning specifications on motor vehicles for the purpose of controlling vehicle emissions. Nothing in this section shall prohibit the alteration or the conversion of a motor vehicle to operate on a gaseous fuel if the resultant emissions are at levels complying with state and federal standards for that model year of motor vehicle.
5. (5) Nothing in this section shall be construed to prevent the adjustment or modification of motor vehicles to reduce vehicle emissions pursuant to section 215 of the federal Clean Air Act, as amended, 42 U.S.C. sec. 7549.

6. (6)

   1. (a) Nuisance exhibition of motor vehicle exhaust - prohibition. A person shall not engage in a nuisance exhibition of motor vehicle exhaust, which is the knowing release of soot, smoke, or other particulate emissions from a motor vehicle with a gross vehicle weight rating of fourteen thousand pounds or less into the air and onto roadways, other motor vehicles, bicyclists, or pedestrians, in a manner that obstructs or obscures another person's view of the roadway, other users of the roadway, or a traffic control device or otherwise creates a hazard to a driver, bicyclist, or pedestrian.

   2. (b) The prohibition set forth in subsection (6)(a) of this section does not apply to:

      1. (I) A commercial vehicle, as defined in section 42-1-102 (17.5);
      2. (II) A common carrier, as defined in section 40-1-102 (3)(a)(I);
      3. (III) A motor carrier, as defined in section 40-10.1-101 (10);
      4. (IV) A motor carrier of passengers, permitted pursuant to section 40-10.1-302;
      5. (V) A motor carrier of towed motor vehicles, permitted pursuant to section 40-10.1-401;
      6. (VI) A motor carrier of household goods, permitted pursuant to section 40-10.1-502;
      7. (VII) A motor vehicle used for agricultural purposes; or
      8. (VIII) Any other vehicle used for commercial activities.
7. (7) If a motor vehicle's emissions control system has been disconnected, deactivated, or rendered inoperable, the division may notify the executive director that the owner of the motor vehicle has violated subsection (1) or (2) of this section.

Source: L. 94: Entire title amended with relocations, p. 2311, § 1, effective January 1, 1995. L. 2017: (3) amended and (6) added, (SB 17-278), ch. 323, p. 1742, § 1, effective June 5. L. 2025: (1) and (2) amended and (7) added, (SB 25-321), ch. 387, p. 2176, § 5, effective June 3.

Editor's note: This section is similar to former § 42-4-1210 as it existed prior to 1994, and the former § 42-4-314 was relocated to § 42-4-312.