Will your car fail the emissions test in IL if check engine light is on?

Yes, your car will fail the emissions test in IL if the check engine light is on. The check engine light is an indicator that there is something wrong with your car's emissions system and that it is not functioning properly. In order to pass the emissions test, your car must be in proper working order and the emissions system must be functioning correctly. If the check engine light is on, it is an indication that there is something wrong with the system and it will not pass the test.