020-13 Wyo. Code R. § 13-2
(a) No person shall intentionally remove, alter or otherwise render ineffective or inoperative, exhaust emission control crank case ventilation or any other air pollution control device or system which has been installed on a motor vehicle or stationary internal combustion engine as a requirement of any federal law or regulation.
(b) No person shall operate a motor vehicle or other internal combustion engine originally equipped with air pollution devices or systems as required by any federal law or regulation unless such devices or systems are in place and in operating condition.
(c) Subsections (a) and (b) of this regulation shall not apply to vehicles or stationary internal combustion engines which have been modified or altered to use a fuel other than gasoline or diesel fuel, except that such units shall comply with existing standards for emissions therefrom.
020-13 Wyo. Code R. § 13-2