What Illinois requires for vehicle emissions testing

Illinois requires emissions testing for most vehicles registered in Cook County and the collar counties (DuPage, Kane, Lake, McHenry, and Will). Vehicles in other Illinois counties do not need emissions tests. The state runs this program through the Illinois Vehicle Emissions Program, which tests whether your vehicle's exhaust meets federal Clean Air Act standards.

You must pass an emissions test before you can renew your vehicle registration in a covered county. The test happens at a licensed emissions testing station — not at a Secretary of State facility. Illinois has about 150 testing stations across the region, and you choose which one to visit.

The test itself takes about 10 minutes. A technician connects a probe to your vehicle's diagnostic port (or tailpipe on older vehicles) and measures nitrogen oxides, particulate matter, and other pollutants. Your vehicle either passes or fails. If it fails, you have 30 days to repair it and retest at no additional charge.

Key Takeaways

  • Emissions testing is required only in Cook County and the five surrounding collar counties; the rest of Illinois has no testing requirement.
  • You must test before renewing your registration, and the test costs between $25 and $35 depending on your vehicle type and the testing station.
  • You can find a licensed testing station through the Illinois Environmental Protection Agency website or by calling 1-800-253-2000.
  • If your vehicle fails, you have 30 days to repair it and retest for free at the same station.
  • Vehicles older than 1996 and certain exempt vehicles (electric cars, motorcycles, trailers) do not need to be tested.

Which vehicles must be tested in Illinois

Not every vehicle on the road needs an emissions test. Illinois exempts vehicles that are too old or too new to produce measurable emissions data, as well as certain vehicle types.

Vehicles model year 1996 and older are exempt from testing. Vehicles model year 2025 and newer are also exempt — they are covered under federal warranty and are assumed to meet standards. Diesel vehicles model year 2010 and newer are exempt. Electric vehicles, motorcycles, mopeds, and trailers do not need testing.

If you own a vehicle in the covered counties that is model year 1997 through 2024, gasoline-powered, and not a motorcycle or trailer, you must test it before registration renewal. Hybrid vehicles follow the same rules as gasoline vehicles.

How to find a testing station and schedule

Illinois does not operate a central scheduling system. You find a station, call or visit in person, and test on a walk-in basis or by appointment depending on the station's policy.

The Illinois Environmental Protection Agency maintains a searchable list of licensed testing stations on its website at www2.illinois.gov/epa. You can filter by county and see each station's hours and phone number. You can also call the state hotline at 1-800-253-2000 to get station locations and hours.

Some stations are busy during certain times of year — typically the weeks before registration renewal important date. Calling ahead to ask about wait times can save you a trip. Many stations accept walk-ins, but some require appointments, especially in high-traffic areas.

What happens if your vehicle fails the test

A failure means your vehicle's emissions exceed the standard for its model year and vehicle class. Common reasons include a faulty oxygen sensor, a loose gas cap, a failing catalytic converter, or engine problems that trigger the check-engine light.

You have 30 days from the test date to repair your vehicle and return to any licensed testing station for a retest. The retest is free — you pay the original test fee only once. The station will give you a printed failure notice that shows which emissions standards your vehicle did not meet.

If you repair your vehicle and it still fails the retest, you can continue to retest within the 30-day window at no charge. Once 30 days have passed, you must pay the full test fee again. If you cannot repair your vehicle in time, you cannot renew your registration in Illinois until you pass a test.

Cost and timing for emissions testing

The test fee varies by vehicle type and testing station. Gasoline vehicles typically cost $25 to $35. Diesel vehicles cost slightly more, usually $30 to $40. Hybrid vehicles are tested as gasoline vehicles and cost the same.

The test itself takes about 10 minutes, but total time at the station depends on how busy it is. During peak times — the month before registration renewal important date — you may wait 30 minutes to an hour. Off-peak times can be much shorter.

You must test before your registration expires. If your registration has already expired, you cannot legally drive the vehicle, and you must renew registration before you can test. Check your registration renewal notice to see when your important date is.

Registration renewal and emissions test coordination

Your emissions test result is valid for one year from the test date. When you renew your registration, the Secretary of State's office checks whether you have a passing test on file. If you do, registration renewal proceeds normally. If you do not, your registration renewal will be denied until you pass a test.

You can test at any point during your registration year, not just at renewal time. Many people test early to avoid the rush in the weeks before their renewal important date. If you test more than a year before your renewal date, you will need to test again before renewing.

The test result is tied to your vehicle's Vehicle Identification Number (VIN), not to you personally. If you sell your vehicle, the test result stays with that vehicle and transfers to the new owner if it is still valid.

What to do if you disagree with a test result

If you believe a test result is wrong, you can request a retest at a different station. You must pay the full test fee again. The second test result is what counts for registration purposes.

If the second test passes, you can contact the Illinois Environmental Protection Agency to report a possible testing error at the first station. The EPA investigates complaints about testing station accuracy and can audit stations that show patterns of incorrect results.

You cannot dispute a test result through the Secretary of State's office. The only remedy is to retest at another station. Keep your test paperwork in case you need to show proof of a retest to the EPA.

Frequently Asked Questions

Can I renew my registration without an emissions test?

No, not in Cook County or the collar counties. The Secretary of State's system will not process your registration renewal without a passing emissions test result on file. If you live outside those six counties, you do not need a test.

What if I just moved to Illinois from another state?

You must obtain an Illinois emissions test before you can register your vehicle in the state, if you live in a covered county. Out-of-state test results are not accepted. You have 30 days from the date you establish residency to register your vehicle.

Do I need to test my vehicle if I only drive it occasionally?

Yes, if you register it in a covered county. Registration and testing are tied together. If you do not plan to drive the vehicle, you can let the registration expire instead, which means you cannot legally drive it on public roads.

What if my check-engine light is on?

You can still test, but your vehicle will likely fail. The check-engine light usually indicates a problem that causes excess emissions. Repair the underlying issue first, then test. Many repair shops can read the diagnostic code for free or low cost.

How long does it take to get my test result?

You get your result when ready after the test. The station prints a pass or fail notice on the spot. The result is also sent electronically to the Secretary of State's office within one business day, so you can renew your registration right away.