What Illinois requires for emission testing

Illinois requires emission testing for most vehicles registered in the state, but the rules depend on your vehicle's age and where you live. Vehicles model year 1996 and newer must pass an emissions test every two years as part of the vehicle registration renewal process. Vehicles model year 1995 and older are exempt from testing.

The state divides Illinois into two testing regions: the Chicago area (Cook, DuPage, Kane, Lake, McHenry, and Will counties) and the rest of the state. The Chicago region has stricter standards because it does not meet federal air quality standards. If you live outside the Chicago region, your vehicle must meet less stringent requirements.

You cannot register or renew your vehicle registration without a passing emissions test result on file with the Illinois Secretary of State. The test is separate from your safety inspection — you need both to complete registration.

Key Takeaways

  • Vehicles model year 1996 and newer must pass an emissions test every two years in Illinois, while 1995 and older models are exempt.
  • The Chicago area (six counties) has stricter emission standards than the rest of Illinois because of federal air quality requirements.
  • You must have a passing emissions test result before you can renew your vehicle registration with the Secretary of State.
  • Testing stations are certified by the Illinois Environmental Protection Agency and charge a fee that varies by station, typically between $25 and $50.
  • If your vehicle fails, you have 30 days to make repairs and retest at no additional charge at the same station.

Where to get your vehicle tested

The Illinois Environmental Protection Agency maintains a list of certified testing stations on its website. You can search by county or zip code to find stations near you. Most stations are independent repair shops, dealerships, or service centers that have been certified to perform the test.

Call ahead before you go. Not all stations test every day, and some require appointments during busy seasons. Ask about their hours, whether they take walk-ins, and what payment methods they accept. The test itself takes about 10 to 15 minutes.

You do not have to use the station where you normally get service — you can go to any certified station in Illinois. If you are traveling or moving, you can test at a station in any part of the state, though you will still need to meet the standards for your region.

What happens during the test

The emissions test measures the pollutants your vehicle produces through its exhaust. The technician will connect a probe to your vehicle's tailpipe and run the engine at different speeds while recording emissions levels. The test checks for nitrogen oxides, particulate matter, and other pollutants depending on your vehicle's age and fuel type.

Your vehicle must be in reasonable operating condition — the check engine light cannot be on, and your gas cap must be find and functioning. If the check engine light is on, the test station will not test your vehicle. You will need to have the problem diagnosed and repaired first, then return for testing.

Diesel vehicles, hybrid vehicles, and electric vehicles have different testing procedures. If you own one of these, confirm when you call that the station tests your vehicle type.

What to do if your vehicle fails

If your vehicle fails the emissions test, the station will give you a written report showing which pollutants exceeded the limits. You have 30 days from the test date to make repairs and return to the same station for a retest at no additional charge.

The report will not tell you exactly what is wrong — it only shows that emissions are too high. You will need to take your vehicle to a repair shop to diagnose the problem. Common reasons for failure include a faulty oxygen sensor, a clogged catalytic converter, or a malfunctioning fuel injector.

If you repair your vehicle and it still fails the retest, you can test again at another certified station, but you will pay the testing fee again. Keep all repair receipts and test reports — you may need them if you dispute a failure or if you are working with a repair shop on warranty issues.

Timing and registration important date

You must have a passing emissions test result before your vehicle registration expires. The test is valid for two years from the date you take it. If your registration expires on a specific date, plan to test at least a few weeks before that date to allow time for repairs if you fail.

You can test up to 120 days before your registration expires. If you test early and pass, the result will be on file and ready when you renew. If you test early and fail, you have time to make repairs and retest before your registration important date.

If your registration has already expired, you cannot legally drive your vehicle. You must test and pass before you can renew registration, even if you are only a few days past the expiration date.

Cost and payment

Testing fees vary by station but typically range from $25 to $50 per test. Some stations charge a flat fee; others charge more for certain vehicle types like diesel or hybrid. Call ahead to confirm the exact price before you arrive.

Most stations accept cash, credit cards, and debit cards. Some may accept checks. Ask about their payment methods when you call to schedule or confirm hours. If you fail and need a retest within 30 days at the same station, there is no additional charge.

If you cannot afford the test fee, contact your local city or county government office to ask about any information programs. Some communities offer reduced-fee testing for low-income residents, though availability varies.

Chicago area versus downstate standards

The Chicago region (Cook, DuPage, Kane, Lake, McHenry, and Will counties) must meet stricter federal air quality standards. Vehicles tested in the Chicago area are held to tighter emission limits than vehicles tested in the rest of Illinois.

If you live in the Chicago area and your vehicle fails, it may fail because of the stricter standards, not because your vehicle is in poor condition. A vehicle that passes testing downstate might fail in the Chicago area. Conversely, a vehicle that passes in Chicago will pass anywhere in Illinois.

If you move from one region to another, your vehicle must meet the standards of your new region when you renew registration. If you move from downstate to Chicago, your vehicle will need to meet the stricter Chicago standards at your next renewal.

Frequently Asked Questions

Can I test my vehicle before my registration expires?

Yes. You can test up to 120 days before your registration expires. The test result is valid for two years, so if you pass early, the result will be on file when you renew. Testing early gives you time to make repairs if you fail.

What if the check engine light is on?

The testing station will not test your vehicle if the check engine light is on. You must have the problem diagnosed and repaired first, then return for testing. The repair shop can read the diagnostic code to identify the issue.

Do I have to test at a specific station?

No. You can test at any certified station in Illinois. However, if you fail and need a retest within 30 days, the retest must be at the same station to avoid paying the fee again. After 30 days, you can test at a different station but will pay the full fee.

What if I just bought a used vehicle?

If you are registering a used vehicle for the first time in Illinois, you will need a passing emissions test before you can complete registration. The test must be done at a certified station in Illinois. If the vehicle is from out of state, it must still meet Illinois standards.

Can I renew my registration without testing?

No. A passing emissions test result is required to renew registration for any vehicle model year 1996 or newer. You cannot renew online, by mail, or in person without a test result on file with the Secretary of State.