About Emissions Testing

Clean Air Car Check performs three different types of emissions tests based on the model year of the vehicle being tested.

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 vehicles. During this test, an inspector drives the vehicle on a treadmill-like device called a dynamometer. The test simulates driving on a road. While driving, the vehicle’s tailpipe emissions are captured and analyzed to determine if the emissions control equipment is working properly. 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.

The vehicle inspection and maintenance program is a requirement of the 1990 federal Clean Air Act Amendments, and is part of Indiana’s overall plan to improve air quality by reducing hydrocarbons, carbon monoxide and nitrogen oxides in Lake and Porter counties. Emission testing improves air quality by ensuring emission controls on passenger vehicles and light duty trucks are working properly to reduce the level of harmful pollutants in the air we breathe.

Test early.  You do not have to wait to receive your registration renewal notice.  A vehicle can be tested as early as October 1st of the year before it is due.  Testing early gives you more time to make repairs if necessary.

Test before repairs.  If you are worried that your vehicle will fail, we recommend testing the vehicle BEFORE making repairs.  Once a vehicle has failed, customers will have access to resources to guide them through the repair and retest process.  Additionally, if a waiver becomes necessary, only repairs made after a failing test can be applied toward the waiver qualification.

Fully warm up your vehicle before testing.  If possible, drive your vehicle for at least 10-15 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 rear brakes.

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.

Make sure your exhaust is intact and leak free. Because we are collecting and analyzing your vehicle’s tailpipe emissions, we must be able to collect an undiluted sample from the tailpipe.  If your exhaust system has leaks we will not be able to perform the test.

Repair any significant fluid leaks prior to testing.  If your vehicle is leaking a significant amount of fluid, we will not be able to perform a test.

Address service engine lights promptly. Addressing issues during your warranty period can save you money in the long run. Read your owner’s 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 monitors.  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.


Is your Indiana vehicle out of state?

Motorists can apply for an Out of State Extension if their vehicle is located more than 300 miles from an Indiana Clean Air Car Check emissions testing station.  This extension will allow the owner to register their vehicle without traveling back to Indiana for a test.  The vehicle will be due for its emissions test once it returns to Indiana.

To apply for an Out of State Extension, the vehicle owner must submit proof of the vehicle’s current location and submit an application, as well as pay a $40 processing fee. Rush processing is also available for an additional $10.

Out of State Extension will not be issued for vehicles located within the State of Indiana or in areas of neighboring states within 300 miles of Northwest Indiana.


Is your out of state vehicle temporarily located in Indiana, but require an emissions test for your home state?

In some circumstances Clean Air Car Check can perform an emissions test for a vehicle from another state that is temporarily located here.  We advise that out of state motorists check with their home state to ensure that a test from Indiana will be accepted.  There is a $50 non-refundable voluntary testing fee for out of state vehicles. Call our customer service hotline at 1-888-240-1684 with questions.

Facility Locations & Hours

  • Crown Point – 755 N. Industrial Blvd. [map]
  • Gary – 3901 W. Fourth Ave. [map]
  • Griffith – 232 Ivanhoe Court South [map]
  • Hammond – 1231 Gostlin St. [map]
  • Hobart – 325 Sullivan St. [map]
  • Portage – 5777 Melton Rd. [map]
  • Valparaiso – 2503 Beech St. [map]

Call us at 888-240-1684 or 219-661-8269


Tuesday – 9 a.m. to 5 p.m.
Wednesday – 9 a.m. to 5 p.m.
Thursday – 9 a.m. to 5 p.m.
Friday – 9 a.m. to 5 p.m.
Saturday – 9 a.m. to 5 p.m.
CLOSED – Sunday, Monday and State Holidays



Vehicles can be inspected beginning in October of the year before they are due to be tested. There is no need to wait for a notice to arrive in the mail, just bring in your vehicle prior to its registration expiration.


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