Air Care Colorado About The Test

What Exactly Gets Tested?

video_FPO.jpgThe "emissions inspection" is actually a series of tests. In addition to the On-Board Diagnostics (OBD) "plug-in" and the I/M 240 dynamometer "treadmill-like" tests (for 1982 and newer vehicles) and the two-speed Idle test (for 1981 and older vehicles, and heavy duty trucks), elements of the emissions test are as follows:

  1. Pretest Safety Check
    As the vehicle enters the building, a brief check around the vehicle is made to make sure there are no visible problems that would make it unsafe to test. The inspector will look for obvious fluid leaks, worn tires, etc. If the vehicle is rejected from testing for safety or other reasons, you will be given a form stating what condition(s) must be corrected before the vehicle can be tested.

  2. Visual Inspection of Emissions Equipment
    All vehicles are given dashboard warning light and gas cap presence and pressure checks. In addition, vehicle model years 1975 through 1995 are given the following equipment checks, to ensure all required equipmwnt is installed, intact, and in apparent working order:
    • catalytic converter
    • air injection system
    • O2 sensor system
    • "check engine" light

    Vehicles not originally equipped with these items are not required to have them. Vehicles that were originally equipped with any of them must have them in place in order to pass the emissions test. Gray market vehicles and customer built vehicles must have components appropriate to their model year, or must present evaluation paperwork from a state Emissions Technical Center.

  3. Gas Cap Pressure Test
    Gas caps on 1975 and newer vehicles are tested for leakage. The cap is removed from the vehicle and attached to a pressurization device. Gas caps that do not have an adequate seal allow hydrocarbon (HC) vapors (raw gasoline) to escape into the atmosphere. Failing this test will cause your vehicle to fail its emissions test. You will need to replace the cap and return your vehicle to an emissions center for a complete retest, not just a gas cap retest. The state requires a complete retest because a vehicle may perform differently once a properly sealed cap is in place. This is particularly true for computer-controlled vehicles.

  4. "Check Engine" Light check
    This is a malfunction indicator and/or maintenance reminder light. Depending on the make and model of the vehicle, it may say "Check Engine," "service engine," or "emissions," or may simply contain an image of an engine. An illuminated "Check Engine" light: 
    • Will cause vehicles eight (8) through 11 years old to fail the inspection.
    • Will be noted as "Advisory" only for vehicles 12 years and older.
  5. Opacity (Smoke) Inspection
    All vehicles are checked for the presence of visible smoke. More than five (5) percent opacity for a duration of five (5) seconds or longer will cause a vehicle to fail.
    **(Smoke failures are not subject to the $75 and $715 repair limit.)

  6. On-Board Diagnostics (OBD) test
    On-Board Diagnostics, known as OBD or OBD II, is a computer-based system built into all 1996-and-newer light-duty vehicles. OBD systems monitor the performance of a vehicle's major components, including those responsible for controlling emissions. The systems continuously check vehicles to ensure they are operating as designed, and to detect emissions-related problems before they might otherwise be noticed.

    • Vehicles eight (8) through 11 years old require an OBD "plug-in" inspection only.
    • Vehicles 12 years old back to model year 1996 will receive an "Advisory" OBD test in addition to the I/M 240 "treadmill-like" test.
    • Vehicles 12 years old through 1996 that cannot be tested using the I/M 240 "treadmill-like" test due to tire size or other configuration issues will be given an alteranate OBD test.
  7. I/M 240 dynamometer "treadmill-like" test 
    Vehicles are driven on a "treadmill-like" device that tests vehicles under simulated driving conditions. A cone is connected to the tailpipe to capture the vehicle's emissions. An "Advisory" OBD "plug-in" test is conducted on all 1996 and newer model year vehicles.

    • Vehicles 12 years old back to model year 1981 require an I/M 240 "treadmill-like" test.
    • Newer vehicles with OBD systems that are not "Ready" or cannot communicate with the station computer will be given an I/M 240 as an alternate test.
  8. Two-speed Idle Test 
    This is a non-driving test that monitors a vehicle's emissions at idle for about 30 seconds, at approximately 2,500 RPM (engine speed) for an additional 30 seconds and again at idle for a final 30 seconds. A cone is connected the tailpipe to capture and evaluate the vehicle's emissions.

    • Vehicles model year 1981-and-older receive two-speed idle tests.
  9. Gas Cap Pressure Test
    Gas caps on 1975 and newer vehicles are tested for leakage. The cap is removed from the vehicle and attached to a pressurization device. Gas caps that do not have an adequate seal allow hydrocarbon (HC) vapors (raw gasoline) to escape into the atmosphere. Failing this test will cause your vehicle to fail its emissions test. You will need to replace the cap and return your vehicle to an emissions center for a complete retest, not just a gas cap retest. The state requires a complete retest because a vehicle may perform differently once a properly sealed cap is in place. This is particularly true for computer-controlled vehicles.