Welcome to the Connecticut Emissions Program

Emissions testing using the On-Board Diagnostic system or OBD testing is the quickest and most efficient of all emissions tests.  The vehicle’s internal computer, which continuously monitors the engine, transmission and emissions control systems are tested. The OBD test is, in effect, an “early warning system” that alerts you to the need for repairs that can reduce air pollution and ensure that your vehicle keeps running as cleanly as it was designed to run.  The inspector will connect a communication cable from the emissions testing equipment to your vehicle’s Diagnostic Link Connector or DLC.  Through the cable, the emissions testing equipment will request specific communication protocols from your vehicle, allowing the testing equipment to verify whether or not your vehicle emissions control system is in compliance.  Information is retrieved from your vehicle; nothing is uploaded or installed on your vehicle.

Vehicles subject to OBD testing includes 1996 and newer gasoline powered and 1997 and newer diesel-powered vehicles with the Gross Vehicle Weight Rating (GVWR) less than 8,501 LBS.

Vehicles with a GVWR between 8,501 LBS to 10,000 LBS, regardless model year, will be subject to a stationary tailpipe test called a Pre-Conditioned Two-Speed Idle (PC TSI). This applies to all fuel types except diesel. All diesel vehicles with a GVWR between 8,501 LBS to 10,000 LBS are subject to a tailpipe test utilizing an opacity testing device.


Please click here for more information on OBD testing.