All 1968 model year and later vehicles are required to have an effective air pollution control device.
All vehicles except those listed below shall be inspected biannually to ensure that air pollution control equipment complies with the exhaust emissions standards defined by the Commissioner of Environmental Protection and approved by the U.S. EPA. OBD is utilized as part of the state emissions inspection process.
The following vehicles are exempt: those with a Gross Vehicle Weight (GCWR) of more than 10,000 lbs.; electric-powered vehicles; motorized bicycles; motorcycles; vehicles manufactured at least 25 years ago; new vehicles at the time of registration; vehicles not designed primarily for highway use; the Toyota Prius, farm vehicles, vehicles operating with temporary registrations, and antique, rare, or special interest motor vehicles.
New vehicles that are 4 or fewer model years old are exempt from emissions testing.
The commissioner may issue a sticker that shows the expiration date of the inspection on both sides, and an expiration date for exempt vehicles.
Inspections may be made at authorized dealer and repair locations.
Used motor vehicles registered in Connecticut from out-of-state are required to pass emission testing and VIN verification before they can be registered.
Visit here for more information on the Connecticut Emissions Program.