About Emissions Testing
HOW WE TEST || WHY
WE TEST || TESTING TIPS ||
HOW WE TEST
Depending on the model year of your vehicle, Clean Air
Car Check uses different types of emissions tests. All
vehicles receive a Gas Cap Pressure Check, which
tests to see if a vehicle's gas cap is effectively keeping
fuel vapors from escaping. Fuel evaporation is a major
cause of ground level smog and a properly functioning
gas cap improves gas mileage by preventing fuel waste.
The Second Generation On-Board Diagnostics (OBD II)
Test is the most common test procedure and is used
to test model year 1996 or newer vehicles. During this
simple test, data is downloaded from the vehicle's on-board
computer to check for emissions equipment malfunctions.
An OBD scanner is attached to a connector typically located
under the vehicle's dashboard.
The Inspection and Maintenance (I/M 93) Test is
used to test model year 1981 through 1995 or newer vehicles.
During this test, an inspector drives the vehicle on a
treadmill device called a dynamometer. The test simulates
driving on a road. While driving, the vehicle's tailpipe
emissions are captured and analyzed to evaluate the effectiveness
of the vehicle's emissions control equipment. It is important
that a vehicle subject to this type of test has an exhaust
system that is intact and leak free. The vehicle also
needs properly functioning brakes and should not have
any major fluid leaks.
The Single Idle Speed (BAR 90) Test is used to
test 1976 to 1980 model year vehicles. A metal probe is
inserted into the vehicle's tailpipe while the vehicle
idles to sample the exhaust stream. At the same time,
a sensor is placed on the hood of the vehicle to measure
the engine speed. The probe measures the vehicle's emissions
and they are analyzed to determine whether or not the
vehicle's emission control equipment is working properly.
The vehicle's exhaust system must be intact and leak free.
WHY WE TEST
Motor vehicle manufacturers are required to meet increasingly
stringent pollution control standards. Vehicles that are
not properly maintained or that have malfunctioning emission
control systems often exceed these standards. Vehicle
emissions testing is designed to identify such vehicles
in order to make necessary repairs to reduce emissions
below the applicable pollution control standards. Just
over 17% of the vehicles tested fail the initial vehicle
emissions inspection. Identifying and repairing these
vehicles has reduced ozone precursor emissions by more
than 4,000 pounds per summer day. These repairs also improve
the vehicle's performance and fuel economy.
The vehicle inspection and maintenance program is a requirement
of the 1990 federal Clean Air Act Amendments, and is part
of the overall plan to improve air quality by reducing
hydrocarbons and nitrogen oxides in Lake and Porter counties.
Emission testing improves air quality by ensuring emission
controls are working properly.
Model years 1976 –
years 1996 and newer
Model years 1976 – 1995
Fully warm up your vehicle before testing.
If possible, drive your vehicle at highway speeds for
at least 15 minutes prior to visiting an inspection station.
Make sure your brakes are in good condition.
Poor brakes are not only a safety hazard, but also make
the vehicle very difficult to test on the equipment and
may cause the vehicle to be rejected from testing.
If your vehicle is rear wheel drive, you must have functioning
Make sure your front wheel drive vehicle is properly
aligned. Poor front end alignment will
make the vehicle difficult to test and may cause the vehicle
to be rejected.
Model years 1996 and newer
Address service engine lights promptly. Addressing
issues during your warranty period can save you money
in the long run. Read your owners manual for
specific warranty information.
Don’t clear your codes. Clearing
your codes or disconnecting your battery may cause you
considerable grief and gas money trying to reset your
An OBD system is made up of monitors that test different
components in the vehicle. Some monitors run all the time
(continuous monitors). Others only run at certain times
or if special conditions are present (non-continuous monitors).
If you clear your codes or disconnect your battery, your
non-continuous monitors will no longer be ready and will
require a variety of driving to get them to set again.
Manufacturers have different drive cycles for their vehicles,
and some monitors are more difficult than others to set,
particularly some 1996 and 1997 model year vehicles. Monitors
that are not ready may cause your vehicle to be rejected
from the inspection.
In order to avoid rejection for an inspection-don't clear
your codes! If your check engine light is on, find out
what Diagnostic Trouble Code (DTC) is causing the light
to turn on, fix the problem and drive the vehicle until
the light goes off. When the light goes off, you know
the problem is fixed. If you are taking your vehicle to
a professional repair technician, have the repair technician
return your vehicle with the light on. After you take
the vehicle through its drive cycle the light should go
off and you will know the problem is fixed.
FREQUENTLY ASKED QUESTIONS
ABOUT THE TESTING
ABOUT EMISSIONS TESTING
Q. Can I really renew my vehicle's
registration at the emissions testing site?
A: Yes! Clean Air Car Check's "Drive-Thru. Renew!"
is an officially certified partner of the Indiana Bureau
of Motor Vehicles. "Drive-Thru. Renew!" offers
partial service license branch transactions, including
the sale of temporary permits, registration renewals,
new registrations, and will soon add titling to the list
of available services. Convenience fees apply.
Q. Why do we need emission testing?
A. The vehicle inspection and maintenance program is
a requirement of the 1990 federal Clean Air Act Amendments,
and is part of the overall plan to improve air quality
by reducing carbon monoxide, hydrocarbons and nitrogen
oxides in Lake and Porter counties. Emission testing improves
air quality by ensuring that vehicles' emission controls
are working properly. This program has contributed to
better air quality in Lake and Porter counties.
Q. Why is there a vehicle emissions program in Lake
and Porter counties?
A. In the Clean Air Act Amendments of 1977, the United
States Environmental Protection Agency designated Lake
and Porter counties as nonattainment areas for ozone levels.
The counties were reclassified as a severe nonattainment
area in the 1990 amendments to the Clean Air Act. This
classification requires areas failing to meet the National
Ambient Air Quality Standards (NAAQS) for ground-level
ozone to develop state implementation plans to attain
and maintain the standard. Enhanced vehicle inspection/maintenance
testing was put into place as a mandated control measure
throughout the Greater Chicago Area, which includes Lake
and Porter counties, northeastern Illinois, and southeastern
Wisconsin. Though Lake and Porter counties were redesignated
to attainment areas in 2010, the vehicle inspection and
maintenance program is a key piece of Indiana's plan to
prevent backsliding so that the area can remain in attainment.
Q. Why does my vehicle need to be tested?
A. Motor vehicles powered by gasoline are significant
contributors to ground level ozone, or smog. Therefore,
testing of these vehicles ensures that emission controls
are working properly and, if not working properly, testing
ensures that vehicles owners make the appropriate repairs
to aid in the reduction of ground level ozone.
Q. How often will my vehicle need to be tested?
A. Your vehicle is scheduled for testing every two years.
The four most recent model years are exempt from testing.
Odd model year vehicles are tested in odd-numbered years
and even model year vehicles are tested in even-numbered
years. For example, a 1996 vehicle will be tested in 2000,
2002, 2004, 2006, 2008, and so on. A 1997 vehicle will
be tested in 2001, 2003, 2005, 2007, and so on.
Q. When does my vehicle need to be tested?
A. Your vehicle will need to be tested before you can
register or renew your vehicle’s registration with
the Bureau of Motor Vehicles.
Q. How will I know when I am due for an emissions
A. The Indiana Bureau of Motor Vehicles (IBMV) currently
notifies all motorists living in Lake and Porter counties
when their vehicles are due for testing. If a test is
needed, "EMISSION TEST REQUIRED" will be printed
on the vehicle registration renewal notice. This notice
is mailed approximately two (2) months before the renewal
deadline. However, you do not have to wait to receive
your notification in the mail before you take your vehicle
in for an emissions test. Vehicles can be tested as early
as October of the year before it is due for testing.
The present vehicle testing schedule is determined by
the month motorists are due to obtain their vehicle registration.
The Indiana Bureau of Motor Vehicles vehicle registration
renewal schedule is as follows:
2011 Vehicle Registration Renewal Schedule
Who Requires Testing
Corporate fleets and trust-owned
Last names AAAA - ARNN
Last names ARNO - BATE
Last names BATF - BLAI
Last names BLAJ - BRID
Last names BRIE - BUSD
Last names BUSE - CHAN
Last names CHAO - CONN
Last names CONO - CURL
Last names CURM - DICE
Last names DICF - EDDY
Last names EDEA - FERG
Last names FERH - FRYA
Last names FRYB - GLOR
Last names GLOS - GUMZ
Last names GUNA - HART
Last names HARU - HILE
Last names HILF - HUCH
Last names HUCI - JERR
Last names JERS - KEEL
Last names KEEM - KNUD
Last names KNUE - LAWR
Last names LAWS - LOPE
Last names LOPF - MART
Last names MARU - MCKI
Last names MCKJ - MILL
Last names MILM - MUND
Last names MUNE - NUNG
Last names NUNH - PATT
Last names PATU - PONT
Last names PONU - REDM
Last names REDN - ROBE
Last names ROBF - SANC
Last names SAND - SERM
Last names SERN - SLON
Last names SLOO - SPRI
Last names SPRJ - SUCE
Last names SUCF - THOP
Last names THOQ - VANO
Last names VANP - WALD
Last names WALE - WATT
Last names WATU - WILK
Last names WILL - WRIG
Last names WRIH - ZZZZ
Q. How much does the emissions test cost?
A. There is no charge for a vehicle emissions test in
Q. Where do I take my vehicle for testing?
A. There are seven Clean Air Car Check stations in Northwest
Indiana. To determine which station is most convenient
for you, call the toll-free Clean Air Car Check hotline
at 1-888-240-1684 or see LOCATIONS
Q. How do I know if the used vehicle I purchased requires
A. A vehicle must receive a passing emissions test and
provide proof to the Indiana Bureau of Motor Vehicles
in order to register and license the vehicle. We advise
shoppers in the market for a used vehicle to call the
toll-free Clean Air Car Check hotline to check the emissions
status of a vehicle before purchasing it. Using the Vehicle
Identification Number (VIN), the testing record can be
retrieved from the Clean Air Car Check database. If the
vehicle was previously tested in an Indiana county requiring
emissions testing, we can inform the potential buyer whether
or not the vehicle passed the most recent vehicle emissions
inspection and when the inspection was conducted.
Q. What vehicles must be tested?
A. In the appropriate model year, passenger vehicles and
light-duty trucks with a gross vehicle weight rating (GVWR)
of 9,000 pounds or less and an engine displacement of
over 200 cubic centimeters must be tested.
Q. What if I do not comply with the vehicle emissions
A. If your vehicle is not in compliance, you will not
be able to be register or renew your vehicle's registration
with the Indiana Bureau of Motor Vehicles.
Q. What vehicles are exempt?
A. Vehicles which are:
- The four newest model year vehicles,
- Model year 1975 and older,
- Powered by electricity or diesel fuel,
- Considered show cars and meet established criteria
for a Show
- Considered kit cars or dune buggies and meet established
criteria for Specialty Exemption,
- Above 9,000 pounds in Gross Vehicle Weight Rating
(GVWR) (this is typically located on the vehicle's door
- Ceremonial vehicles,
- Off-highway construction equipment,
- Have an engine displacement of less than 200 cubic
- Recreational vehicles (Specifically RVs that are manufactured
for the sole purpose of recreation, not vehicles that
have been modified for recreational use), and,
- Registered for farm use only (including tractors).
Q. Why aren’t diesel vehicles’ emissions
A. Diesel exhaust contains relatively low levels of hydrocarbons
(HC), carbon monoxide (CO) and nitrogen oxides (NOx),
which are the pollutants that react with sunlight to form
Q. What is my vehicle tested for?
A. The test consists of a gas cap pressure test that checks
to see if your gas cap is doing its part to stop evaporative
emissions from your gas tank. Inspectors also check under
your vehicle to ensure that all the emissions monitoring
components are intact. Clean Air Car Check will measure
your vehicle for emissions of hydrocarbon (HC), carbon
monoxide (CO), and nitrogen oxides (NOx). High emission
levels of any of these pollutants indicate that the vehicle
is not using fuel efficiently and, as a result, is contributing
to poor air quality. For vehicles that are 1996 or newer,
the On-Board Diagnostic system provides information about
which emission control components are functioning properly.
Q. What effect do hydrocarbons, carbon monoxide and
nitrogen oxide have on the environment?
A. Hydrocarbons are unburned gasoline particles that contribute
to the formation of ground-level ozone, often referred
to as smog. Carbon monoxide is a colorless, odorless gas
formed from partially burned fuel that can adversely affect
mental function, visual focus, alertness, and can even
cause death. Nitrogen oxides, when mixed with other compounds,
can contribute to ground- level ozone, acid rain, water
quality deterioration, and global warming.
Q. What is ozone?
A. Emissions from gasoline powered vehicles can lead to
the formation of ground-level ozone, which can cause eye
and throat irritations, respiratory distress, and damage
breathing passages, making it difficult for the lungs
Q. How is ozone formed?
A. Ozone is formed near the ground in a photochemical
1) Gasoline, paints and solvents evaporate, thereby releasing
2) Cars and factories burn fossil fuels, releasing nitrogen
3) Heat and sunlight trigger a photochemical reaction
between these emissions, transforming them into ground-level
ABOUT THE TESTING PROCEDURE
Q. How long will the test take?
A. Once the vehicle enters the first testing position,
the three-step test should only take about ten minutes.
Q. Why do some of the lanes at the emissions test
site move faster than others?
A. There are many reasons this may occur. Vehicles of
different ages are subject to different test procedures.
Some test types take longer than others. Fluid leaks,
exhaust system problems, idling problems, and insufficient
warming of the vehicle's engine can create problems with
vehicle testing. Customers without the proper paperwork
such as the vehicle's registration or the repair data
form can also cause delays. Be assured that we will test
your vehicle as quickly as possible.
Q. Why do all of the car accessories have to be turned
A. Electrical accessories can interfere with the electronic
sensing of the engine speed and can also adversely affect
the test results.
Q. How does the test procedure work?
A. For model year 1996 and newer vehicles, a Second Generation
On-Board Diagnostics (OBD II) system test is performed.
This test does not require the vehicle to be driven on
the dynamometer. A scan tool is plugged into the vehicle's
OBD connector, which reads the vehicle's computer to check
the status of the OBD system.
For model year vehicles 1981 - 1995, the emissions check
has three steps. During the first step, an inspector will
complete a basic visual inspection for leaking fluids
and conditions that may present a safety problem. The
inspector will verify the Vehicle Identification Number
(VIN) and the Gross Vehicle Weight Rating (GVWR) for trucks
or vans. The lane inspector will then inspect for the
presence of a catalytic converter and conduct a gas cap
pressure check. The motorist will be asked to exit the
vehicle and proceed to an enclosed, climate-controlled
During the second step, the vehicle is placed on the
dynamometer, a treadmill-like device, and secured in place.
The lane inspector will enter the vehicle and "drive"
the vehicle, following a drive trace projected on a screen
in front of the vehicle. "Driving" the vehicle
on the dynamometer simulates normal driving situations,
including accelerating, decelerating, braking, and stopping.
The vehicle is operated between speeds of 0 - 33 mph.
Emissions are collected as the vehicle is driven. If a
vehicle does not pass the emission test during the first
testing cycle, a second-chance test is automatically given.
When the test is completed, the lane inspector exits the
vehicle. (NOTE: During the second step, a well-maintained
vehicle may be able to "fast pass" after the
first 30 seconds of the emissions test.)
During the third step, the motorist returns to the vehicle.
At this time, the inspector presents the vehicle emission
For model year vehicles 1976 - 1980, the three testing
steps are similar except that these vehicles will not
be tested on the dynamometer. The vehicle's emissions
are checked while the vehicle is idling. The inspector
inserts a probe into the vehicle's tailpipe, which collects
the emissions for measurement
Regardless of the type of test a vehicle receives, customers
may be able to take advantage of Clean Air Car Check's
onsite partial license branch services "Drive-Thru.
Renew!". If the vehicle fails or rejects, motorists
may be eligible to purchase a temporary permit, and if
the vehicle passes, "Drive-Thru. Renew!" can
renew the vehicle's registration onsite.
Q. What if my vehicle fails the emissions test?
A. The lane inspector will provide you with a Vehicle
Inspection Report that states that the vehicle has failed
the emissions test. The inspector will also provide additional
materials that provide information on how to get your
vehicle repaired. More information is available at the
customer service entrance of the Clean Air Car Check station
or by calling the toll-free hotline at 1-888-240-1684.
Q. Where should I take my vehicle for repairs?
A. Any repair facility may repair your vehicle's emission
system. However, in order to qualify for a waiver
for a vehicle that is model year 1981 or newer, should
that be necessary, the repairs must have been completed
by an Indiana
Certified Emission Repair Technician (ICERT) Facility.
A list of ICERT shops will be provided to you before you
leave the test site if your vehicle fails.
Before choosing a shop, informed customers should ask:
If you have any other questions,
please call the Clean Air Car Check toll-free hotline at