There is no limit to how many times you can fail an emissions test in Illinois. The Vehicle Emissions Inspection Law sets no cap on failures or retests. What matters is your registration renewal deadline: as long as you pass, get a waiver, or otherwise comply before your emissions sticker expires, the number of attempts in between does not count against you. Retests are free, so the practical constraint is time, not tries.
The Deadline That Actually Matters
Your compliance deadline is the expiration date of your current emissions sticker, which lines up with your registration renewal. The clock does not start when you fail. It ends when your sticker does. Testing early in the cycle is the single best thing you can do, because it gives you room to diagnose, repair, retest, and, if needed, apply for a waiver before the Secretary of State’s office refuses to renew your plates.
What a Failure Gives You
A failed test produces a Vehicle Inspection Report listing the specific diagnostic trouble codes (DTCs) that triggered the failure. Those codes tell you and your mechanic exactly which emission control systems are misbehaving. Keep the report. You will need it for retesting, and you will need it in more detail if repairs do not resolve the problem and you end up applying for a waiver.
A rejection is not the same as a failure. If too many onboard monitors are in a “not ready” state, the station will turn the vehicle away without running the test. For 2001 and newer models, only one monitor can be “not ready.” For 1996 through 2000 models, two can be. Rejections do not count as attempts, but they still leave you without a passing result and eat into your window.
Retesting After Repairs
Once your mechanic has addressed the trouble codes, you go back to an official testing station. The retest is free, and you can repeat it as many times as necessary. Use the station locator on Illinois.gov to find a site.
One trap catches people on retests. If your original failure involved catalytic converter codes (P0420 through P0439), the catalyst monitor must read “ready” when you return. Battery disconnects and certain repairs reset the monitors, and they need drive time to complete their self-checks. Show up too soon and the station will reject the vehicle rather than test it. Put miles on the car before you retest, especially after any work that touched the battery or the emissions system.
Applying for a Repair Cost Waiver
If your vehicle keeps failing despite honest repair efforts, the Illinois EPA can issue a repair cost waiver that lets it pass without meeting standards. You have to meet each of the following:
- You have failed at least one retest after repairs.
- You have spent at least $450 on emissions-related repairs, not counting work to correct tampering.
- The repairs address the DTCs from your initial failure.
- The qualifying repairs were performed no more than 30 days before your current test eligibility date.
- All emission control devices are present, connected, and operational.
- Your Malfunction Indicator Lamp (check engine light) works. A burned-out or disabled MIL disqualifies you.
You will need signed receipts identifying your vehicle by VIN, describing the diagnostic procedures used, explaining why the repairs were appropriate for the failure, and itemizing the cost of each eligible repair. Submit the application to the Illinois EPA. If approved, the waiver is issued to the vehicle owner or to a designee named in a written authorization.
What Happens If You Miss the Deadline
Missing the deadline does not fine you for the failed tests themselves. It blocks your registration. The Illinois EPA and the Secretary of State’s office share enforcement, and a non-compliant vehicle simply cannot be renewed.
Driving on expired plates because you have not finished the emissions process is a petty offense. Fines are at least $50 if you are caught within 60 days of when the new or renewal sticker was required, and at least $300 after 60 days. A third or subsequent violation within one year of the first is a Class C misdemeanor. A suspended registration also cannot be transferred to another vehicle until the suspension is lifted, so the problem does not stay confined to one car in your driveway.
If Your Vehicle Is Out of State
If your Illinois-registered vehicle lives in another state that also requires emissions testing, you do not have to bring it back. Apply for reciprocity compliance through the Illinois Air Team by submitting proof that the vehicle passed, received a waiver, or otherwise complied where it is located. The proof cannot be more than four months old relative to your Illinois test-by date. The online form is the fastest route, though email, fax, and mail submissions are accepted. Reciprocity does not help if the vehicle is in a state that does not test at all; in that case, you would look at an exemption based on the vehicle being located outside the testing area.