Since the test is stationary, the noise created gives the perception that the tires are rolling at a much higher rate of speed. The equipment used to test gasoline powered vehicles in the Air Team testing station is different from the equipment used to test diesels. The Illinois Department of Transportation has responsibility for the testing of heavy-duty diesel powered trucks over 16,000 lbs. These vehicles receive the basic idle test that also is given to pre- 1981 vehicles. A. Gasoline caps that work properly keep harmful fumes from escaping.
Fumes escaping from the gas tank contribute to the formation of ground-level ozone.
Currently, OBD testing is being performed on 1996 and newer vehicles on an advisory basis only. The results of this procedure do not affect whether your vehicle passes or fails the emissions test. The test is designed especially for computer controlled vehicles, and it monitors emissions control systems for fault codes. A connector, generally located under the driver's side dashboard, is used so the information can be downloaded from the vehicle's computer to the testing station's computer. The codes are printed on the motorist's Vehicle Inspection Report to help automotive repair technicians diagnose emissions related problems.