What Counties in Illinois Require Emissions Testing?

Ten counties in Illinois require emissions testing: Cook, DuPage, Lake, Kane, Kendall, McHenry, Will, Madison, Monroe, and St. Clair. Cook, DuPage, and Lake are covered in full, so every registered vehicle owner in those three counties falls inside the program. The other seven are covered only in the zip codes closest to the Chicago and Metro-East St. Louis urban areas. Your vehicle’s registration address is what determines whether the requirement reaches you, and the test itself is free.¹

Fully Covered Counties

If your vehicle is registered anywhere in Cook, DuPage, or Lake County, you are inside the testing area regardless of city or municipality. These three counties form the core of the Chicago metropolitan testing zone, and there are no zip code exceptions within their borders.¹

Partially Covered Counties

Seven more counties sit only partly inside the testing area. The statute works by listing the zip codes that are excluded from each county. If your registration address falls in one of the excluded zip codes below, you do not need an emissions test. If your county is on this list but your zip code is not among the exclusions, testing is required.¹

Chicago-Area Collar Counties

Kane County excludes these zip codes: 60109, 60119, 60135, 60140, 60142, 60144, 60147, 60151, 60152, 60178, 60182, 60511, 60520, 60545, and 60554.

Kendall County excludes 60447, 60450, 60512, 60536, 60537, 60541, 60545, 60548, and 60560. Portions of 60543 outside the census-defined urbanized area are also excluded.

McHenry County excludes 60001, 60033, 60034, 60071, 60072, 60097, 60098, 60135, 60142, 60152, and 60180.

Will County is partially covered, with specific zip codes excluded by statute. The excluded list is extensive, and Will County residents should verify status through the Illinois Air Team website or the Secretary of State’s office rather than guess.

Metro-East St. Louis Counties

Madison County excludes 62001, 62012, 62021, 62026, 62046, 62058, 62061, 62067, 62074, 62086, 62088, 62097, 62249, 62275, 62281, and 62293.

Monroe County excludes 62244, 62248, 62256, 62261, 62264, 62276, 62277, 62278, 62279, 62295, and 62298.

St. Clair County excludes 62224, 62243, 62248, 62254, 62255, 62257, 62258, 62260, 62264, 62265, 62269, 62278, 62282, 62285, 62289, 62293, and 62298.

How Your Registration Address Decides

The state looks at the address on your vehicle’s registration to decide whether you are inside the testing area. It does not matter where you actually drive or park the vehicle. If you recently moved into or out of one of these counties, an outdated registration address can either trigger a testing requirement you don’t have or let you slip past one you do. Keeping the registration current prevents both problems.¹

Living in a Covered County Does Not Automatically Mean Testing

The county map is only the first filter. Your vehicle also has to be the kind of vehicle the program applies to, and it has to be old enough to have entered the cycle.

The program covers most gasoline-powered passenger vehicles from model year 1996 or newer, but only once they are four years old. A 2022 model, for example, is first tested in 2026.² After that, testing runs on a biennial schedule tied to model year: even-model-year vehicles are tested in even calendar years, and odd-model-year vehicles in odd calendar years.³ Heavy-duty vehicles with a gross vehicle weight rating between 8,501 and 14,000 pounds are tested only if they are model year 2007 or newer; older heavy-duty vehicles in that weight range are exempt.⁴

Several categories of vehicle never need a test, even in a fully covered county:⁵

Diesel and all-electric vehicles. The OBD test targets gasoline engine emissions.
Motorcycles and motorized pedal cycles, including mopeds and motor-driven cycles.
Vehicles of model year 1967 or older, plus vehicles registered as antique, expanded-use antique, custom, or street rod.
Farm vehicles, including implements of husbandry.
Vehicles registered and tested in another state whose program Illinois recognizes.
Vehicles with a Junking Certificate from the Secretary of State.

One point causes regular confusion. The general model-year cutoff for the active requirement is 1996, not 1967. Vehicles from 1968 through 1995 sit in a gray zone: the statute exempts vehicles of model year 1995 or earlier that did not have an expired emissions sticker as of February 1, 2007. In practice, almost no vehicles that old are still being flagged, and the 1996 model year is where the active requirement begins.⁵

If you live in one of the ten counties, your vehicle uses gasoline, it is a 1996 or newer model, and it is at least four years old, you should expect a notice from the Illinois EPA when your testing year comes up. You can also check your status any time through the Illinois Air Team website using your VIN.²

1
Justia. Illinois Code 625 ILCS 5 Chapter 13C – Emission Inspection
2
Illinois Environmental Protection Agency. Vehicle Emissions Testing Program
3
Illinois Air Team. Does My Vehicle Need to be Tested
4
Illinois Air Team. FAQs
5
Illinois General Assembly. Illinois Code 625 ILCS 5 13C-15