Va. Code § 46.2-1048
No motor vehicle registered in the Commonwealth and manufactured for the model year 1973 or for subsequent model years shall be operated on the highways in the Commonwealth unless it is equipped with an air pollution control system, device, or combination of such systems or devices installed in accordance with federal laws and regulations.
It shall be unlawful for any person to operate a motor vehicle, as herein described, on the highways in the Commonwealth with its pollution control system or device removed or otherwise rendered inoperable.
It shall be unlawful for any person to operate on the highways in the Commonwealth a motor vehicle, as described in this section, equipped with any emission control system or device unless it is of a type installed as standard factory equipment, or comparable to that designed for use upon the particular vehicle as standard factory equipment.
No motor vehicle, as described in this section, shall be issued a safety inspection approval sticker unless it is equipped as provided under the foregoing provisions of this section or if it violates this section.
The provisions of this section shall not prohibit or prevent shop adjustments or replacements of equipment for maintenance or repair or the conversion of engines to low polluting fuels, such as, but not limited to, natural gas or propane, so long as such action does not degrade the antipollution capabilities of the vehicle power system.
The provisions of this section shall not apply to converted electric vehicles.
Va. Code § 46.2-1048