Most gasoline-powered vehicles in Maryland that are model year 1996 or newer and are registered in certain counties require an emissions test every two years. Vehicles older than 20 model years are generally exempt. So, for example, in 2024, a 2004 model year car would need a test, while a 2003 model year car would be exempt.
The requirement is based on a rolling 20-year exemption. The Maryland Motor Vehicle Administration (MVA) uses an On-Board Diagnostics (OBD-II) test for vehicles model year 1996 and newer. This involves plugging a scanner into your car's computer port to check for emissions-related faults. Vehicles model years 1977 to 1995 undergo a two-speed idle test, which measures tailpipe emissions while the engine idles and runs at a higher RPM.
The counties requiring testing are: Anne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles, Frederick, Harford, Howard, Montgomery, Prince George's, Queen Anne's, and Washington, as well as Baltimore City. Diesel-powered vehicles with a Gross Vehicle Weight Rating (GVWR) under 8,501 lbs and model year 1997 or newer also require testing, but have different protocols.
| Vehicle Model Year | Test Type | Typical Testing Frequency | Exemption Status (Example for 2024) |
|---|
| 2024 | OBD-II Scan | Every 2 years upon registration renewal | Not exempt |
| 2010 | OBD-II Scan | Every 2 years upon registration renewal | Not exempt |
| 2004 | OBD-II Scan | Every 2 years upon registration renewal | Requires Test |
| 2003 | Two-Speed Idle (if tested) | N/A | Exempt (20+ years old) |
| 1998 | OBD-II Scan | Every 2 years upon registration renewal | Not exempt |
| 1996 | OBD-II Scan | Every 2 years upon registration renewal | Not exempt |
| 1995 | Two-Speed Idle | Every 2 years upon registration renewal | Not exempt |
| 1985 | Two-Speed Idle (if tested) | N/A | Exempt (20+ years old) |
The best way to confirm your vehicle's status is to check your registration renewal notice from the MVA or use the online vehicle lookup tool on the Maryland VeRIP website. Electric vehicles are exempt from emissions testing entirely.
