Emissions Program Passenger Cars & Light Duty
In 2005, the state of New Hampshire implemented statewide
OBD II emissions testing. This means that vehicles will need
to pass the OBDII emissions test in order to pass the annual
The OBD II test is part of the annual vehicle safety inspection.
When your mechanic finishes the safety inspection on your vehicle,
he/she will enter the results of your inspection into a computer
(NHOST unit) that gathers and stores test result data. If your
vehicle is a 1996 or newer car or light duty truck (8,500 lbs.
GVWR or less), the computer will prompt the mechanic to perform
an OBD II test. To perform the OBD II test, the mechanic will
attach a cable to the data link connector (DLC) in your car.
This will enable your car's computer to communicate with the
test equipment. The computer in your car will then relay data
about your vehicle's emission components to the NHOST unit.
At the conclusion of the test, the NHOST computer will print
a Vehicle Inspection Report (VIR) that will provide you with
detailed information about your inspection results. The mechanic
will sign the VIR and give it to you along with any other informational
pages that print.
OBD II emissions testing is part of the Environmental Protection
Agency (EPA) Clean Air Act Amendments of 1990. All cars and
light duty trucks manufactured in 1996 or later are required
to have second generation on board diagnostics (OBD II) computers
to monitor engine conditions and components. The OBDII computer
helps to assure that the engine is running at peak efficiency
and also alerts you to any malfunctioning emissions control
components that require attention. When the OBDII system detects
a problem with the emission control system, a "check engine"
or "service engine soon" light (also called a Malfunction Indicator
Light or MIL) is illuminated on the dashboard. If your vehicle's
MIL is illuminated, it will not pass inspection and you will
not be issued a windshield inspection sticker until proper repairs
have been completed.
By continuously monitoring the well being of your vehicle's
components, the OBD system can identify minor problems that
can be repaired easily before they become more serious and expensive
to correct. Not only can you save money on repairs, but you
will also get better gas mileage, which will save you money
at the pumps!
OBDII systems are very complex, so it is important to have
qualified technicians make the repairs to your vehicle. When
shopping for emissions-related repair service, be sure to ask
if the mechanics performing emissions repairs to your vehicle
are ASE A-8 or L-1 certified.
Thank you for doing your part to keep your vehicle safe and
the air clean.