The Illinois vehicle emissions test checks whether the emission control system on your motor vehicle is working properly. Motor vehicle manufacturers are required to meet increasingly stringent pollution standards, but vehicles that are not properly maintained or that have malfunctioning emission control systems often exceed these standards. Vehicle emissions tests identify such vehicles, and repairs are then required to reduce the emissions which cause pollution. These repairs help clean the air while improving the vehicle's performance and fuel economy.
Your vehicle is scheduled for testing every two years, beginning the fourth model year. If you purchase a vehicle that has an expired vehicle emissions compliance certificate or sticker, the vehicle may be required to be tested as soon as the new registration is received. Vehicles failing the emissions test must be repaired, then retested. If your vehicle failed the emissions test, we recommend that you have the vehicle repaired by a qualified technician who is experienced in the diagnosis and repair of emission control systems. If a vehicle cannot pass the emissions test, a waiver may be available if certain requirements are met. Check the waiver section of the “Questions about Vehicle Emissions Testing” FAQ page for further information about waiver requirements.)
Please see our helpful Test Day Tips to ensure success on test day.