Vehicle Emissions Testing

Illinois Emissions Inspection & Smog Laws

In Illinois all eligible vehicles must go through emissions inspection every 2 years. This “smog” check includes a test of your car’s emissions to determine whether smog emissions are within tolerance.

Illinois smog laws summary:

Illinois laws require emissions testing for gasoline powered passenger vehicles, trucks and buses older than 4 years, but not older than 1996. Emissions testing (smog testing) is done in the following Illinois counties: Cook, Dupage, and Lake, and certain ZIP codes in Kane, Kendall, McHenry, Will, Madison, Monroe, and St. Clair counties.

The following article will give you the basics of smog laws in Illinois. Below you can find out how smog checks are performed in the state of Illinois, and which vehicles can be exempt from the laws. This article is based on latest Illinois regulations in effect since November 2016.

Which counties require emissions inspection?

Emissions testing in Illinois is only required in the following counties:

  • Cook
  • Dupage
  • Lake

Only certain zip codes in the following counties require smog testing. Vehicles within zip codes specified below are excluded from Illinois emissions testing laws:

  • Kane (excluded zip codes: 60109, 60119, 60135, 60140, 60142, 60144, 60147, 60151, 60152, 60178, 60182, 60511, 60520, 60545, and 60554)
  • Kendall (excluding zip codes: 60447, 60450, 60512, 60536, 60537, 60541, those parts of 60543 that are not within the census defined urbanized area, 60545, 60548, and 60560)
  • McHenry (excluding zip codes: 60001, 60033, 60034, 60071, 60072, 60097, 60098, 60135, 60142, 60152, and 60180)
  • Will (excluding zip codes: 60401, 60407, 60408, 60410, 60416, 60418, 60421, 60442, 60447, 60468, 60481, 60935, and 60950)
  • Madison (excludes zip codes: 2001, 62012, 62021, 62026, 62046, 62058, 62061, 62067, 62074, 62086, 62088, 62097, 62249, 62275, 62281, and 62293)
  • Monroe (excluding zip codes: 62244, 62248, 62256, 62261, 62264, 62276, 62277, 62278, 62279, 62295, and 62298)
  • St. Clair (excluding zip codes: 62224, 62243, 62248, 62254, 62255, 62257, 62258, 62260, 62264, 62265, 62269, 62278, 62282, 62285, 62289, 62293, and 62298)

Which vehicles require emissions testing?

Your vehicle requires emissions test in Illinois if:

  • It is older than four years, but a model newer than 1996
  • It runs on gasoline and is a passenger vehicle
  • It is a truck or bus

New Illinois residents must first register their vehicle before conducting emissions test. Your test notice will specify when you must do your smog check.

Valid emissions test is required for completing vehicle registration, renewal, or reinstating a suspended registration. Emissions test is valid for 2 years, after which your vehicle must be retested.

When purchasing a vehicle from a private owner, it is the buyer’s responsibility to get a valid emissions test. When purchasing vehicles from used car dealers, the dealer must issue a valid emissions test.

Which vehicles are exempt from smog testing?

Diesel-powered vehicles or those newer than 4 years are exempt from smog check. Motorcycles are also not undergoing emissions testing. Further exempt vehicles include:

  • Vehicles which are not subject to registration.​
  • Diesel-powered vehicles and vehicles that are powered exclusively by electricity.
  • Motorcycles, motor-driven cycles and motorized pedal-cycles.
  • Antique vehicles, expanded-use antique vehicles, custom vehicles, street rods, and vehicles of model year 1967 or before.
  • Vehicles of model year 1995 or before that were in compliance with the Illinois Vehicle Emissions Inspection Law on February 1, 2007.
  • Farm vehicles and implements of husbandry.
  • Vehicles registered in, subject to, and in compliance with the emissions inspection requirements of another state.
  • Vehicles for which a Junking Certificate has been issued by the Secretary of State pursuant to the Illinois Vehicle Code (625 ILCS 5/3-117).
  • Implements of warfare owned by the State or federal government.
  • Vehicles of model year 2006 or earlier with a manufacturer gross vehicle weight rating between 8,501 and 14,000 pounds.
  • Vehicles with a manufacturer gross vehicle weight rating greater than 14,000 pounds.

Vehicles with out of state registration are also exempt from Illinois smog check.

How emissions testing works?

For most 1996 and newer passenger cars and light duty trucks, vans and sport utility vehicles, and 2007 and newer heavy duty vehicles with gross weight rating between 8,501 and 14,000 pounds, an On-Board Diagnostics (OBD) test is used.

OBD testing consists of connecting a scanning tool to your vehicle’s on-board computer to determine if there are any issues with your vehicle.

Which emissions control devices are tested?

Assuming your vehicle was originally manufactured with them, the following emissions control devices may be tested during emissions testing:

  • Catalytic converter (CAT)
  • Exhaust gas recirculation valve (EGR)
  • Positive crankcase ventilation system (PCV)
  • Air injection system (AIS)
  • Evaporative emissions control (EVAP)
  • Fuel inlet restrictor (FIR)
  • Thermostatic air cleaner (TAC)

Illinois emissions testing locations

To find your nearest emissions inspection station see this webpage:

What happens is emissions testing fails?

Failing emissions testing means your vehicle will have to be repaired and re-tested before you can pass the smog inspection. It is recommended to choose a Recognized Repair Technician.

Upon failing a smog check your will receive the following documents:

Based on these documents your emissions inspector or repair technician will help you determine how to repair your vehicle, assuming it is required.

What if repairs fail?

If your vehicle does not meet emissions or smog standards set by Illinois emissions test laws, you can apply for a waiver or have your vehicle repaired. Waivers are issued if:

  1. Your vehicle failed the initial and subsequent smog test.
  2. Your vehicle’s emissions components are present and operational.
  3. A recognized repair technician made the repairs.
  4. All repairs under emissions control warranties have been done.
  5. You spent at least $450 in emissions related repairs (you will need to provide either receipts as evidence, or a signed statement from technician who performed the repairs).

How much are emissions testing fees?

Emissions testing requires a $20 fee. Some counties may not charge a fee.

When you pass safety and emissions inspection, don’t forget to keep your receipt. This will serve as proof of your completed inspection and you may require it at a later date.

Please note we only provide this information about vehicle emissions for informational purposes. You should always double-check current official Illinois laws and regulations to ensure this information is correct.

Sources & references:

  1. Vehicle Testing Locations
  2. Illinois Air Team – Vehicle emissions testing program information (Illinois EPA)
  3. Illinois EPA – Vehicle emissions testing
  4. Illinois Compiled Statutes – Vehicle Code, Chapter 13C – Emission Inspection
This article about Illinois Emissions Inspection & Smog Laws was last updated in 2024. If any of our information is incomplete or outdated please let us know. Thank you!