What to Know About Illinois Vehicle Emissions Testing

The Illinois Environmental Protection Agency requires emissions testing to help improve air quality and public health — especially in urban areas, like Chicago, where reducing air pollution from motor vehicles is a top priority. Drivers living in Illinois may need to periodically complete emissions testing on their vehicles.

Most cars made after 1996 require emissions testing if they’re 4 or more years old and if the car owner lives in a certain county, including those that surround Chicago and border St. Louis.1 Some people and vehicles are exempt from these rules, but most drivers will need to comply with these testing requirements.

Here’s what you need to know about Illinois emissions testing requirements.

How emissions testing works in Illinois

While not all states require regular emissions or smog testing, Illinois state law does.2 The Clean Air Act requires the Environmental Protection Agency (EPA) to set certain National Ambient Air Quality Standards (NAAQS), which help protect the environment and public health. The EPA advises emissions testing to help improve air quality and reduce greenhouse gas emissions.3

Because the air quality in certain parts of Illinois exceeds the ozone NAAQS, drivers in some areas of the state must comply with regular emissions testing. Due to the Illinois Vehicle Emissions Inspection Law of 2005, drivers living in a county or ZIP code with air pollution issues must complete emissions testing if their car is built after 1996 and more than 4 years old. This inspection typically occurs when the vehicle’s license plate expires.

During emissions tests in Illinois, most cars undergo an onboard diagnostics (OBD) test, which involves using a scanning tool to monitor a car’s onboard computer. This tool checks the OBD system status through a readiness check and identifies whether the malfunction indicator light is on. The scanning tool can also retrieve any stored diagnostic trouble codes.4

The car will likely pass the OBD test if the OBD system works.

Cost of vehicle emissions testing in Illinois

Emissions testing typically costs around $20. You’ll need to go to an official testing site, which you can find using the Illinois Air Team’s repair shop locator.

It’s a good idea to get your vehicle emissions testing done several weeks before your vehicle registration expires. You can find the expiration date on your license plate sticker.5

You could face a fine of up to $300 if you don’t do emissions testing.6

Illinois emissions testing requirements

If an Illinois car manufactured after 1996 qualifies for regular emissions testing, the owner must complete an emissions test every two years once the car reaches 4 years old. If a car fails an emissions inspection, the owner will need to have it retested after completing any necessary repairs. Cars that require emissions testing must complete testing to renew registration.

Counties that require emissions testing

Drivers need to pass an emissions test if they live in counties near large cities, like Chicago and around St. Louis. Vehicles need to pass an emissions test every two years if you live in Cook, Lake, or Dupage counties. Exemptions may apply in other counties, depending on your ZIP code.

If you live in one of the following Illinois counties, you may have to get emissions testing:

• Cook

• Dupage

• Kane

• Kendall

• Lake

• Madison

• McHenry

• Monroe

• St. Clair

• Will

Failure to get an emissions test on time can result in fines ranging from $50 to $300 or more. Confirm your vehicle’s testing status online using the state’s Vehicle Eligibility Check tool if you’re unsure if you need a test.

Vehicles that must complete emissions testing

The majority of gasoline-powered vehicles built during 1996 or later require testing if they’re 4 years or older. Here’s a closer look at the types of vehicles that typically need emissions tests:

• Passenger cars

• Light-duty trucks, including SUVs and vans

• Heavy-duty vehicles 2007 model year and newer with a gross vehicle weight rating (GVWR) between 8,501 and 14,000

Vehicles exempt from emissions testing

Not all vehicle types require Illinois emissions testing. Vehicles exempt from emissions testing include the following:7

• Vehicles that don’t require registration

• Diesel-powered vehicles

• Electric vehicles (but not hybrids)

• Cars built in 1967 or before

• Antique vehicles

• Custom vehicles

• Street rods

• Custom vehicles

• Motorcycles

• Farm and husbandry vehicles

• Vehicles registered in another state that remain compliant with that state’s emissions laws

• Vehicles with a junking certificate

• Government-owned war vehicles

• 2006 and earlier vehicles with a GVWR between 8,501 and 14,000 pounds

• Vehicles with a GVWR higher than 14,000 pounds

How to complete emissions testing in Illinois

You’ll need to take the following steps to complete emissions testing in Illinois:

• Prepare for an emissions test. To avoid failing an emissions test, first confirm that your check engine light is off and that the OBD system is operating. Also confirm that your car’s diagnostic link connector isn’t damaged, inaccessible, or missing before you take your vehicle to an Illinois vehicle emissions testing facility.

• Find a testing center. To find Illinois emissions test locations, use the Illinois Air Team Testing Station Locator. Warm your vehicle up by driving it for at least 15 minutes before arriving for your test.

• Complete the inspection. The testing process usually lasts between 15 and 40 minutes. Costs vary for this test, but it typically costs around $20.

What to do if you fail emissions testing

Your vehicle may fail inspection for many reasons. Common reasons include certain emissions systems not functioning properly or wear and tear causing gasoline vapors and pollutants to escape into the environment. Keeping up with regular maintenance, such as replacing your spark plugs, can help avoid issues that may cause emissions testing failure.

If your car fails an emissions test, you can still drive it, but you need to repair the issue that caused the failure before retesting. After a failed test, you’ll receive the following documents to help you and a repair technician determine how to make the necessary repairs:

• Vehicle inspection report (VIR) with test result details

• Repair shop report (RSR) with a snapshot with a list of nearby repair facilities

• Repair data form (RDF) to be completed by a repair technician

The Illinois EPA recommends having repairs made by an expert technician trained in emissions diagnosis and repair. After the repair, the technician must complete and submit the RDF, or you can bring it with you when you return to the inspection facility for a recheck.

In some cases, you may qualify for a repair waiver. To qualify for a waiver, you must fail at least two emission tests, complete a minimum of $1,146 in repair costs, have all vehicle emission control devices present and working, and have the repairs done by a licensed technician.8

Illinois emissions testing FAQs