Why Do I Need to Have my Vehicle Inspected?
The federal Clean Air Act requires vehicle inspection & maintenance (I/M) programs for areas exceeding pollution standards.  Vehicles are a major cause of pollution, and good air quality is better for the environment and for everyone's health.

What is OBD?
On-Board Diagnostics 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.

What is the Check Engine light?
Also known as the Malfunction Indicator Light (MIL), this is a warning for vehicle owners that a problem has been detected in the emission control system.  Your vehicle will be rejected if the light is on when it is tested.

Can I Still Drive my Vehicle with the Check Engine Light On?
Yes.  Check your Owner’s Manual.  However, 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.  Early diagnosis and repair can help prevent more costly repairs later.  It is important not to wait too long before taking your vehicle to a trained (ASE L-1 Certified) mechanic.

How do I Help Make My Vehicle Pass 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.

What should I expect when my vehicle is inspected?
Inspection information from both the Safety and Emission inspections will be entered into the NHOST system and electronically transferred to the DMV.  Vehicles subject to OBD inspections get the OBD test.  The mechanic is required to give a copy of the official Vehicle Inspection Report (VIR) to the motorist every time the vehicle is inspected.

Which vehicles have to be OBD tested?
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 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.

Possible OBD Rejections
Your mechanic will provide more information and discuss why your vehicle was rejected. Rejections can be due to several reasons, including:

• Not Ready- The system in your vehicle is not ready to be tested. This could be due to recent repairs or if the battery was recently disconnected. In most cases, a week or so of normal driving should make your system ready. If it takes more than a week, you should have the vehicle checked, as there may be another problem.
  
• Non-Communication- Your vehicle will not communicate with the test system.  Make sure the Data Link Connector (DLC) is accessible or has not been damaged.
  
• Check Engine Light is On- The most common failure.  The VIR will print Diagnostic Trouble Codes (DTCs) related to the specific problem to help a qualified mechanic diagnose the problem and needed repair.

What if My Vehicle is Rejected?
First, check for warranties on the vehicle.  Federal law requires manufacturer warranties for 8 years or 80,000 miles on the OBD computer and catalytic converter on 1995 and newer vehicles.  Also, check for recalls and Technical Service Bulletins (TSB).  The inspection results on the Vehicle Inspection Report (VIR) will help mechanics to determine necessary diagnostics and repairs.  The NHOST system is a testing device, not a diagnostic tool.  Diagnostics and repairs should be performed by a trained, qualified mechanic.

If your vehicle passes safety and fails emissions 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.

Terms to Know

DLC - Data Link Connector
DTCs - Diagnostic Trouble Codes
MIL - Malfunction Indicator Light or Check Engine Light
NHOST – Test Equipment used to test and transmit testing data
OBD - On-Board Diagnostics
Rejected - Vehicle did not pass the OBD inspection
TSB – Technical Service Bulletin
VIR - Vehicle Inspection Report

For more information please visit the links below:

NH Consumer Information
NH Station and Mechanic Information
USEPA OBD FAQs
USEPA Benefits of OBD
On-Board Diagnostics in I/M

State of NH OBD Program: (603) 271-8800
Economic Hardship Waiver: (603) 271-0352

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