What Chicago requires and who has to test
Chicago requires an emissions test every two years for most gasoline vehicles registered in Cook County. The test measures what comes out of your tailpipe — carbon monoxide, nitrogen oxides, and particulate matter — to confirm your car meets state pollution standards. Diesel vehicles, motorcycles, and vehicles under 8,500 pounds registered outside Cook County are exempt, though some surrounding counties have their own testing programs.
You must pass the test before you can renew your vehicle registration. The Illinois Secretary of State's office will not process your renewal without a passing result. If your registration expires before you test, you cannot legally drive the vehicle on public roads in Illinois.
Key Takeaways
- Chicago emissions tests happen every two years and are required to renew your vehicle registration with the Illinois Secretary of State.
- The test costs between $25 and $30 at any state-certified testing station, and you can find locations through the Illinois Environmental Protection Agency website.
- Your vehicle must be in reasonable working condition — a check engine light or obvious mechanical problems will cause a test failure.
- You receive your test result when ready on paper, and the station sends the result electronically to the state within 24 hours.
- If you fail, you have 30 days to repair your vehicle and retest at no additional cost at the same station.
Where to find a testing station and what it costs
The Illinois Environmental Protection Agency maintains a searchable list of certified testing stations on its website. You can filter by zip code or address to find stations near you. Most are independent repair shops, quick-lube facilities, or dedicated emissions testing centers. Call ahead to confirm hours and whether they accept walk-ins or require an appointment — many stations book up during peak renewal periods.
The test costs between $25 and $30. This is a state-set fee, so price does not vary between stations. Some stations may charge an additional fee if you need a retest after failing, though many include one free retest in the initial fee. Ask when you call.
What happens during the test and why vehicles fail
The technician will plug a probe into your vehicle's diagnostic port (usually under the steering wheel) and run the test while your engine idles. The whole process takes 10 to 15 minutes. You will see your results on a printout before you leave — the station does not withhold results pending review.
Vehicles fail most often because of a check engine light, which is an automatic failure regardless of what the light means. A faulty oxygen sensor, catalytic converter problems, or a loose gas cap can trigger the light. Other common failures include excessive emissions readings, which usually point to worn spark plugs, a clogged air filter, or fuel system issues. If your vehicle has not been serviced recently or you notice rough idling, get a basic tune-up before testing.
Vehicles that have been sitting unused for weeks sometimes fail on the first test but pass after a few days of normal driving. The engine needs to run through its normal operating cycles to clear temporary faults.
What to do if you fail the test
You have 30 days from the test date to repair your vehicle and retest. You do not need to return to the same station, but many stations waive the retest fee if you come back to them. Keep your test paperwork — you will need the test number to prove you tested within the required window.
If repairs are expensive or your vehicle is old, you may be able to claim a waiver. Illinois allows waivers for vehicles that fail emissions but have already spent $500 or more on repairs in the past 12 months, or for vehicles 15 years or older that fail for the first time. You must explore for the waiver through the Illinois Environmental Protection Agency, not through the testing station. The waiver process takes several weeks, so do not wait until your registration is about to expire.
How to renew your registration after passing
The testing station sends your passing result to the state electronically within 24 hours. You do not need to do anything — the result appears in the Secretary of State's system automatically. You can then renew your registration online through the Illinois Secretary of State website, by mail, or in person at a DMV facility.
Online renewal is fastest and costs $148 for a two-year passenger vehicle registration (fees vary by vehicle type and weight). You will need your current registration card, vehicle identification number, and proof of insurance. The renewal is processed when ready, and you can print your temporary registration while your new sticker is mailed to you.
What happens if your registration expires before you test
If your registration lapses, you cannot legally drive the vehicle. You will need to test and renew before you can use the car again. The Secretary of State does not extend important date for emissions testing — the test must be completed before renewal is processed.
If you are pulled over with an expired registration, you face a fine starting at $100. If you were unable to test because the vehicle was broken down or you were out of state, you can request a late renewal through the Secretary of State's office, but this does not waive the emissions requirement. The vehicle must still pass before the registration is valid.
Emissions testing in surrounding counties
Cook County (which includes Chicago) requires testing every two years. DuPage, Kane, Lake, and Will counties have their own testing programs with similar requirements. If you live in one of these counties but work or spend significant time in Cook County, you only need to test in the county where your vehicle is registered.
Some counties allow you to test at stations in neighboring counties if you have a valid reason — for example, if you live near a county border. Call the Illinois Environmental Protection Agency to confirm whether your station choice is allowed before you test.
Frequently Asked Questions
Can I test my vehicle before my registration expires?
Yes. You can test up to 60 days before your registration expires. This gives you time to repair and retest if you fail. Testing early is a good strategy if your vehicle is older or you are unsure whether it will pass.
What if I move out of Cook County after I register my vehicle there?
You must follow the testing rules of the county where your vehicle is registered, not where you live. If you move to a county that does not require testing, you still need to test in Cook County when your registration comes due. If you move to another testing county, you can switch your registration to that county at your next renewal.
Do I need to bring anything besides my car to the testing station?
Bring your current registration card and a photo ID. Some stations also ask for proof of insurance, though this is not always required for the test itself. Call ahead to confirm what the station needs.
What if the testing station closes or goes out of business after I test there?
Your test result is already in the state system, so the station closing does not affect your registration renewal. You can renew with the Secretary of State using the result you received on paper.
Can I test in a different state if I travel there before my registration expires?
No. Illinois only accepts emissions tests from Illinois-certified stations. If you are out of state when your registration is about to expire, you must return to Illinois to test before you can renew.