The I/M 240 Emissions Test
 The I/M 240 test is much more effective than
older technologies for identifying polluting vehicles. It tests for carbon monoxide (CO), hydrocarbons (HC)
and oxides of nitrogen (NOx) during a simulated driving cycle. The vehicle is placed on a treadmill-like
device, or dynamometer, and typical driving activities such as idling, cruising, acceleration and
deceleration are performed while pollution is collected from the tailpipe.
The name of the I/M 240 test means "Inspection and Maintenance,
" with 240 representing the length of the treadmill test in seconds (240 seconds, or four minutes).
Pollutants are measured in grams per mile (gpm), and emissions limits are set by vehicle type and model
year.
1982 and newer gasoline-powered passenger cars
and light duty trucks must be tested every other year as a condition of
obtaining a vehicle registration. 1981 and older vehicles are tested annually with the
Two-Speed Idle Test.
Test Process
 An
inspector guides the vehicle into the inspection lane and performs a brief safety check, enters the
vehicle identification number (VIN) into the computer and makes a visual inspection of required emissions
equipment. Customers go to an enclosed waiting area from which they can observe the inspection.
The vehicle is positioned with its drive wheels on the dynamometer, allowing it to be tested under
actual driving conditions. A fan is positioned in front of the vehicle to simulate wind and keep the engine
cool throughout the test. During the driving simulation, emissions are collected from the tailpipe and
analyzed. On the basis of emissions data, some very clean vehicles receive a "fast pass" while others have to be tested for the full four-minute cycle.
An automatic "second
chance" test is provided for vehicles that fail by a small margin. If the vehicle fails
within 200% of a pollution limit, the computer will instruct the inspector to run a second test. This is
done to minimize the chance that a vehicle might fail simply because of an anomalous situation. For example,
the vehicle may fail because it was not sufficiently warmed up.
 The
vehicle is moved off the dynamometer and the gas cap seal test is performed. The customer is given a
Vehicle Inspection Report detailing the test results and
the inspection fee is collected. If the vehicle passes (and most do) you will
be given a "Vehicle Inspection Report" when the emissions fee is
collected. If the vehicle fails,
you will be provided with a list of local repair facilities ranked by emissions repair success and a
computer report providing useful information to assist the repair technician.
All-Wheel Drive/Traction Control Vehicles
Vehicles that are full-time four wheel drive, all-wheel drive or
traction control are tested using specially-designed dynamometers -- one set for the front wheels and an
adjustable set (adjusted based on length of wheel base) under the rear wheels. The far right lane of every
test station contains two sets of dynamometers and four-wheel drive vehicles are tested in this lane.
Vehicles that can be shifted from four-wheel drive to two-wheel drive must be tested in two-wheel
drive rather than using the four-wheel dynamometers.
Because of OEM design and/or safety considerations, some 1982 and newer
vehicles are not tested on the dynamometer, but are instead tested with the
Two-Speed Idle Test. These include but are not limited to:
Corvette, 2005, low-profile stock tires;
Cadillac Escalade EXT model, all wheel drive with a wheel base of greater than 125
inches, 2002 newer;
Cooper Mini S, 2002;
Daihatsu Rocky, all
wheel drive, 1991;
Dodge
Dakota Quad Cab, optional full-time four-wheel drive model with a wheel
base of greater than 125 inches, 2000 and newer;
Dodge Stealth R/T, all
wheel drive, with manufacturer-equipped 17 or 18 inch wheels, 1991 and newer;
Ford Special Edition
Jack Roush Mustang, 2000 and newer;
GMC
Sierra Denali XL model, all wheel drive with a wheel base of greater than
125 inches, 2002 and newer;
GMC Yukon Denali XL
model, all wheel drive with a wheel base of greater than 125 inches, 2001
and newer;
Isuzu Vehicross, all
wheel drive, 1999-2002;
Landrover Defender 90,
all wheel drive, 1994, 1995 & 1997;
Mercedes-Benz 500, V-8
with traction control, 1990 and newer;
Mercedes-Benz 600 SL
and 600 SEL, 1992 and newer;
Mitsubishi 3000 GT,
all wheel drive, with manufacturer-equipped 17 or 18 inch wheels, 1991 and newer;
Porsche Carrera C-4 and
4S Coupe, Cabriolet and Targa models, all wheel drive, 1989 and newer;
Porsche 911 Twin
Turbo,
all wheel drive, 1996 & 1997;
Toyota Rav 4, two-door,
all wheel drive, 1996;
Volvo 850, with
manufacturer-equipped 17 or 18 inch wheels, 1993-1996;
Kit, custom or homemade cars,
all model years;
Handicapped-plated
vehicles with adaptive equipment such as hand controls and lacking foot pedals, all model years;
Stretch limousines
having a wheel base of greater than 125 inches, and having non-disengagable all-wheel/four-wheel drive
or non-disengagable traction control systems, all model years.
An Important Note About Tire Size
Tires that are smaller than 17 inches or larger
than 34 inches cannot be safely tested on the dynamometer.
Only vehicles with manufacturer-equipped
undersized or oversized tires that do not fit safely on the dynamometer will
be authorized by the state to undergo an idle test instead of a dynamometer
test. Vehicles with tires larger or smaller than original equipment that do
not fit safely on the dynamometer must be returned to stock condition for
testing. Vehicles with non-original undersized or oversized tires will not
receive authorization from the state for an idle test.
Exemptions
A few vehicles are exempt from emissions testing.
Click here to view the list.
More Information
What happens if my vehicle fails the test?
How do I find quality emissions repairs?
What if my vehicle has non-standard equipment?
How can I maximize my vehicle's chances of passing the test?
View emissions limits for passenger cars,
light trucks, and heavy trucks. |
