Emissions Testing in Connecticut

Testing Requirements

Current Testing Requirements in Connecticut

Connecticut operates a statewide biennial emissions testing program for light-duty vehicles. The program applies to most gasoline-powered vehicles, including hybrids, as well as certain diesel vehicles. Testing is performed at a network of privately owned certified test centers managed by Opus Inspection under contract with the DMV. The primary test for model year 1996 and newer vehicles under 8,500 pounds is an OBD-II inspection. Medium-duty vehicles from 2008 and newer with a gross vehicle weight between 8,501 and 10,000 pounds also receive the OBD-II test. Older and heavier gasoline vehicles may receive a pre-conditioned two-speed idle test. A gas cap pressure test and a visual catalytic converter inspection are also part of the process for applicable vehicles.

Who Needs an Emissions Test

Most gasoline-powered vehicles model year 2001 and newer registered in Connecticut must pass a biennial emissions test. This includes passenger cars, light trucks, SUVs, and hybrid vehicles. Diesel vehicles from certain model years may also be subject to testing depending on weight and configuration. Vehicles within their first four model years are exempt from testing. Vehicles model year 2000 and older are statutorily exempt. Electric vehicles, motorcycles, motorized bicycles, and vehicles with a gross vehicle weight rating over 10,000 pounds are permanently exempt. Vehicles operating under dealer, repairer, or transporter plates are also excluded.

How Often Tests Are Required

Emissions testing is required every two years. The DMV assigns each eligible vehicle a biennial due date tied to its registration. Vehicle owners receive a testing notice approximately 45 days before the due date. If the vehicle is tested by its scheduled due date, the next test will be assigned two years from that due date. Vehicles tested more than 30 days late will be assigned a new future due date that reflects the balance of the two-year cycle or a minimum of one year, whichever is greater.

Where Emissions Testing Is Required

Emissions testing is required statewide in Connecticut. There are no county or regional exemptions. All eligible vehicles registered anywhere in the state must be tested regardless of location. This applies equally to urban and rural areas.

What Happens During the Test

For model year 1996 and newer light-duty vehicles, a technician connects to the OBD-II diagnostic port and checks for stored trouble codes, readiness monitor status, and the malfunction indicator lamp. A lit check engine light results in failure. Older vehicles may receive a tailpipe test using an acceleration simulation mode or a two-speed idle test. All applicable vehicles also receive a gas cap pressure test and a visual inspection confirming the catalytic converter is present and has not been tampered with. A missing or malfunctioning gas cap causes failure. The test takes approximately 15 to 30 minutes depending on the vehicle and test type.

Areas in Connecticut That Require Emissions Testing

All areas of Connecticut require emissions testing. Cities and towns where testing applies include Hartford, New Haven, Bridgeport, Stamford, Waterbury, Norwalk, Danbury, New Britain, Bristol, Meriden, West Hartford, Greenwich, Fairfield, Milford, Hamden, Manchester, East Hartford, Middletown, Shelton, Torrington, Norwich, New London, Groton, and Windham. Rural communities across the state follow the same requirements. Certified test centers are distributed throughout Connecticut, and drivers may visit any test center regardless of where they live or where their vehicle is registered.

How the Emissions Test Works in Connecticut

Drivers take their vehicle to any certified emissions test center in the state. There are two types of centers: full-service test centers that handle all eligible vehicles regardless of fuel type or model year, and OBD Plus test centers that handle all vehicles except pre-1997 diesel vehicles. No appointment is required at most stations, though some accept them. Bring your vehicle registration and identification. The test fee is $20, set by state law. Stations accept cash and may accept checks or credit cards at their discretion. If the vehicle passes, the results are recorded electronically with the DMV and registration can be renewed. If the vehicle fails, the owner has 60 days to complete repairs and return for a retest. The first retest is free if performed at the same facility. A $20 late fee is assessed if a vehicle is not tested within 30 days of its due date. A second $20 late fee may apply if a failed vehicle is not retested within 60 days. Registration renewal will be denied if the vehicle has not passed its required emissions test. Waivers may be available if the owner has spent at least $1,137 (as of 2025, adjusted annually by the Consumer Price Index) on qualifying emissions-related repairs at a Certified Emissions Repair Facility and the vehicle still cannot pass.