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How to Pass an Auto Emissions Test

To get or renew your vehicle registration, and cut down on pollution, you may need to pass an emissions or smog check test.


  • Step 1: Get an oil change and tune up Get an oil change and tune up, and check your air filter. Make sure there are no fluid leaks, dashboard warning lights on, or safety issues.
  • Step 2: Inflate tires Make sure your tires are properly inflated, in good condition, and are the original size for your vehicle. If you installed the wrong size tires, it may affect the test equipment or not allow the test to be performed at all.
  • Step 3: Have a gas cap Have a proper gas cap on your car. A vehicle without one automatically fails the test.
  • Step 4: Take it for a drive If you only drive the car rarely, take it for a 30-minute or longer ride the week of the test, preferably on the highway.
  • Step 5: Fill it with premium Fill up your tank with premium gas, which is cleaner and better for the environment.
  • TIP: Consider adding fuel additives to the gas tank, which clean carbon deposits in your engine and lower emission levels.
  • Step 6: Drive on test day On test day, drive your car at least 30 minutes right before the test so it will reach optimal operating temperature.
  • TIP: Try to get the test within 15 minutes of your arrival, so the car is still warmed up.
  • Step 7: Bring your paperwork Bring your DMV paperwork with you to the testing facility so they can scan the bar code it contains. If not, you may pay extra for them to look up the vehicle identification number.
  • FACT: The Clean Air Act of 1970 gave the Environmental Protection Agency authority to regulate motor vehicle pollution.

You Will Need

  • Oil change and tune up
  • Properly inflated tires
  • Gas cap
  • 30-minute highway drive
  • Premium fuel
  • DMV paperwork
  • Fuel additives (optional)

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