On-Board Diagnostics (OBD) is a computer-based system built into all 1996 and newer light-duty passenger vehicles to monitor the performance of some of the engine's major components, including emission control components. The OBD system helps the motorist know if their vehicle has a defect that could cause excess pollution. In addition, it helps mechanics accurately diagnose problems and make effective repairs.
1996 and newer model year light-duty gasoline-fueled passenger vehicles (8500 GVWR and less) and 1997 and newer model year light-duty diesel passenger vehicles (8500 GVWR and less) must have an OBD test as part of the inspection process.
1996 and newer vehicles subject to the OBD inspection are required to pass the test and will need to have repairs done if the vehicle is "Rejected." Only one, sixty (60) day repair period is allowed per inspection cycle for vehicles rejected for OBD failures. Address OBD rejections early so that there is sufficient time to complete the needed repairs.
Check Engine Light
The Check Engine Light, also known as the Malfunction Indicator Light (MIL), is a warning for vehicle owners that a problem has been detected in the emission control system. If the light comes on and stays on, the OBD system has detected a problem. This could be as minor as a loose gas cap or as major as an emission component failure. Your vehicle will be rejected if the light is on when it is tested.
Passing the OBD Inspection
Ongoing vehicle maintenance is the best way to keep your vehicle running properly and ready for inspection. Many of the emission control components can be checked and repaired during routine service. Follow the manufacturer's recommended maintenance to help your vehicle run at its best. This will also help get better gas mileage.
A rejection indicates that a problem exists that could compromise the efficiency and smooth operation of your vehicle. Rejected vehicles must be repaired and pass the inspection before an inspection sticker will be issued. A one time, 60-day repair period will be allowed to have necessary diagnostics and repairs performed, and to have the vehicle re-tested to verify repairs.
If your vehicle passes the safety inspection but fails the OBD inspection and you cannot afford the repairs to the emissions, you may be eligible for an Economic Hardship Waiver to allow more time to save the money to complete the repairs. For an application call the DMV OBD Program at 271-0352.
Reasons for OBD Rejections
Your mechanic will provide more information and discuss why your vehicle was rejected. Rejections can be due to several reasons, including:
For more information please visit the links below:
New Hampshire Division of Motor Vehicles | 23 Hazen Drive | Concord, NH 03305
TDD Access: Relay NH (800) 735-2964