Utah Code
Title 41 Motor Vehicles
Chapter 6a Traffic Code
Section 1626 Mufflers -- Prevention of noise, smoke, and fumes -- Air pollution control devices.
41-6a-1626. Mufflers -- Prevention of noise, smoke, and fumes -- Air pollution control devices.
(1) (a) A vehicle shall be equipped, maintained, and operated to prevent excessive or unusual noise.
(b) A motor vehicle shall be equipped with a muffler or other effective noise suppressing system in good working order and in constant operation.
(c) A person may not use a muffler cut-out, bypass, or similar device on a vehicle.
(2) (a) Except while the engine is being warmed to the recommended operating temperature, the engine and power mechanism of a:
(i) gasoline-powered motor vehicle may not emit visible contaminants during operation;
(ii) diesel engine manufactured on or after January 1, 1973, may not emit visible contaminants of a shade or density darker than 20% opacity; and
(iii) diesel engine manufactured before January 1, 1973, may not emit visible contaminants of a shade or density darker than 40% opacity.
(b) A person who violates the provisions of Subsection (2)(a) is guilty of a class C misdemeanor.
(3) (a) A motor vehicle equipped by a manufacturer with air pollution control devices shall maintain the devices in good working order and in constant operation.
(b) For purposes of the first sale of a vehicle at retail, an air pollution control device may be substituted for the manufacturer's original device if the substituted device is at least as effective in the reduction of emissions from the vehicle motor as the air pollution control device furnished by the manufacturer of the vehicle as standard equipment for the same vehicle class.
(c) A person who renders inoperable an air pollution control device on a motor vehicle is guilty of a class B misdemeanor.
(4) Subsection (3) does not apply to a motor vehicle altered and modified to use clean fuel, as defined under Section 59-13-102, when the emissions from the modified or altered motor vehicle are at levels that comply with existing state or federal standards for the emission of pollutants from a motor vehicle of the same class.
