What Illinois emissions testing requires

Illinois requires emissions testing for most vehicles registered in Cook County and the collar counties (DuPage, Kane, Lake, McHenry, and Will). If you live outside those six counties, you do not need an emissions test. The test checks whether your vehicle's exhaust meets state pollution standards — specifically, it measures nitrogen oxides, particulate matter, and other pollutants your engine produces.

You must pass an emissions test before you can renew your vehicle registration in a required county. The test is separate from your safety inspection; you need both. Illinois does not combine them into a single inspection visit.

Vehicles from model year 1996 and newer are subject to testing. Diesel vehicles, motorcycles, and vehicles registered as salvage or non-operational are exempt. If your vehicle is newer than the current model year minus 3 years, you may be exempt from testing in your first registration year — check with your testing station about your specific vehicle's model year.

Key Takeaways

  • Emissions testing is required only in Cook County and the five collar counties; all other Illinois counties do not require it.
  • You must pass an emissions test to renew your registration, and the test is separate from your safety inspection.
  • The test costs between $20 and $30 depending on your vehicle type and the testing station you choose.
  • You can find approved testing stations through the Illinois Environmental Protection Agency website or by calling 1-800-253-5747.
  • If your vehicle fails, you have 30 days to repair it and retest at no additional cost before your registration expires.

Where to get your vehicle tested

Illinois contracts with private testing stations to perform emissions tests. These stations are spread throughout the required counties, and you can use any approved station — you do not have to go to a specific location based on where you live or work.

To find a testing station near you, visit the Illinois Environmental Protection Agency website at epa.illinois.gov and use their station locator tool. You can also call the Illinois EPA at 1-800-253-5747 and ask for stations in your area. The locator shows each station's address, hours, and phone number so you can call ahead if you want to confirm wait times.

Testing stations are typically open during business hours, Monday through Friday, and some offer Saturday hours. Bring your vehicle registration, proof of insurance, and a valid ID. The test itself takes about 10 to 15 minutes once you are in the testing bay.

What happens during the test

The emissions test is performed on a dynamometer — a machine that measures your vehicle's exhaust while your engine runs under controlled conditions. The technician will drive your vehicle onto the machine, connect a probe to your exhaust pipe, and run your engine through a series of acceleration and idle cycles. You do not drive the vehicle yourself during the test; the technician operates it.

The machine records your vehicle's emissions and compares them to Illinois standards. The test takes about 10 to 15 minutes total. You will receive a printed result when ready after the test is complete. If your vehicle passes, the result is valid for two years and you can renew your registration. If your vehicle fails, you receive a detailed report showing which pollutants exceeded the standard.

Some stations offer a pre-test inspection for an additional fee (usually $10 to $20). This checks your vehicle's basic systems — spark plugs, air filter, fuel pressure — before the official test. A pre-test can help you identify problems that might cause a failure, but it is not required.

What to do if your vehicle fails

If your vehicle fails the emissions test, you have 30 days from the test date to have it repaired and retested. You do not pay for the retest if it happens within 30 days. After 30 days, you must pay the full testing fee again.

The failure report will tell you which emissions systems are not working correctly — for example, a faulty oxygen sensor, a problem with the catalytic converter, or an issue with the fuel injection system. Take this report to a mechanic and have them diagnose and repair the specific problem. Do not assume you need a complete engine overhaul; most failures are caused by one or two specific parts.

After repairs are complete, return to any approved testing station and request a retest. Bring your original failure report with you. Once you pass, you can renew your registration when ready. If you fail a second time, you have another 30 days to repair and retest.

Cost and timing for registration renewal

The emissions test costs between $20 and $30 depending on your vehicle type (gas, hybrid, or diesel) and the individual testing station. Some stations charge the same fee for all vehicle types; others charge slightly more for hybrids. Call ahead to confirm the exact price at your chosen station.

You must complete your emissions test before your registration expires. If your registration is expiring soon, schedule your test at least two weeks in advance to allow time for repairs if you fail. Testing stations can have wait times of several days during peak periods, especially in late summer and early fall.

Once you pass the test, you have 30 days to renew your registration with the Illinois Secretary of State. You can renew online at cyberdriveillinois.com, by mail, or in person at a Secretary of State office. Bring your emissions test result with you or have it ready when you renew online.

Vehicles that do not need testing

Diesel vehicles are exempt from emissions testing in Illinois, even if they are registered in a required county. Motorcycles, mopeds, and vehicles registered as non-operational or salvage title are also exempt. Vehicles registered as classic cars or antiques may be exempt depending on their registration type — contact the Illinois Secretary of State to confirm.

If your vehicle is brand new (model year 2024 or 2025, depending on the current year), you may not need to test in your first registration year. Check with your testing station or the Illinois EPA about your vehicle's specific model year and registration date.

What to do before your test

Before you go to the testing station, make sure your vehicle is in reasonable running condition. Check that your engine light is not on; if it is, have a mechanic scan the code before testing. Make sure your gas cap is tight and your fuel tank is at least one-quarter full. may support your tires are properly inflated and your battery is in good condition.

If your vehicle has been sitting unused for more than a month, drive it for at least 15 minutes before testing to warm up the engine and clear out any stale fuel. This can help prevent a failure caused by a cold start.

You do not need to have your vehicle serviced or detailed before testing. The test measures your exhaust emissions, not your vehicle's appearance or interior condition.

Frequently Asked Questions

Can I test my vehicle in a different county than where I live?

Yes. You can use any approved testing station in any of the six required counties, regardless of where your vehicle is registered. If you live in Cook County but work in DuPage County, you can test at a station near your workplace.

What if I move out of a required county after I register my vehicle?

You do not need to retest when you move. Your vehicle's registration is valid for two years from the date you passed the test. When you renew your registration in your new county, you will only need an emissions test if your new county requires one.

How long does a retest take if I fail the first time?

A retest takes the same 10 to 15 minutes as the original test. You can schedule a retest at any approved station within your 30-day window. Some stations allow you to schedule a retest when ready after a failure; others require you to call or visit in person to book it.

What if my vehicle fails twice?

You have another 30 days from your second failure to repair and retest. If your vehicle fails a third time, you may be required to have a more detailed diagnostic performed by a certified emissions repair facility. Contact the Illinois EPA at 1-800-253-5747 for guidance on next steps.

Can I renew my registration before I pass the emissions test?

No. You must have a passing emissions test result before you can renew your registration in a required county. If your registration expires before you pass, your vehicle registration becomes invalid and you cannot legally drive it.