Section 4531 - Emission control systems(a) Compliance with established maximum levels.--No vehicle manufactured in compliance with the requirements of the Clean Air Act (77 Stat. 392, 42 U.S.C. § 1857 ), or any amendments or supplements thereto, shall have emissions exceeding the maximum permissible levels prescribed by law.(b) Limitation on alteration of system.--No person shall disable, change or alter the emission control system of a vehicle. Original emission control components or replacements in kind shall be present and functioning on all vehicles. A subject vehicle may be equipped with any added components which are designed to improve emissions. It is unlawful for a subject vehicle that is not in compliance with the preceding requirements to be operated under its own power until a reinspection at an official emission inspection station establishes its full compliance, provided that it shall be lawful for the vehicle to be operated under its own power by the vehicle owner while en route to the official emission inspection station for a reinspection.(c) Limitation on sale and operation of vehicles with altered systems.--No person shall knowingly sell or operate a vehicle whose emission control system has been disabled, changed or altered from its original design specifications, except for in-kind replacement of system components and added components which are designed to improve emissions. 1976, June 17, P.L. 162, No. 81, § 1, effective 7/1/1977. Amended 1992, Dec. 16, P.L. 1250, No. 166, § 1; 1994, Dec. 28, P.L. 1450, No. 172, § 7, effective in 60 days.