How Long Does an Emissions Test Take

Smoky Exhaust Pipe
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As a car owner, there comes a time when you must take your vehicle in for an emissions test. Emissions testing is typically required every year or two as part of the vehicle registration renewal process.

The Clean Air Act of 1990 established stricter pollution standards for emissions from cars and trucks. The standards aim to reduce tailpipe emissions of carbon monoxide, hydrocarbons and nitrogen oxides. The act requires most vehicles to undergo periodic testing to ensure they meet emissions standards.

When Are Emissions Tests Required?

Emissions testing requirements vary from state to state. In Arizona, gas-fueled vehicles from 1980 and older need an emissions test every year. Vehicles from 1981 and newer need a test every two years. In Colorado, new vehicles do not need an emissions inspection their first seven years, but vehicles from 1982 and newer need a test every two years. Illinois requires testing of cars 1996 and newer. There, even model-year vehicles are tested during even years and odd model-year vehicles are tested in odd years.

States may only require regular testing in counties that have more traffic congestion and higher rates of air pollution. Missouri, for example, only requires emissions testing in five counties that include and surround St. Louis. In those counties, car owners must do an emissions test every two years.

Most states also have their own exemptions for vehicles that do not need emissions testing. These may include alternative fuel vehicles, motorcycles, vehicles that are 25 years or older and farm vehicles.

It’s always a good idea to look into your state’s requirements for emissions tests and exemptions so you know when and if you’re required to do them. The good news is, if it’s time for you to get an emissions test, getting one is relatively painless.

How Long is an Emissions Test Good For?

Emissions tests are included as part of your state Department of Motor Vehicles (DMV) renewal. In most states, an emissions test is valid for 90 days. In Georgia, the emissions test is valid for 12 months.

Familiarize yourself with your state’s requirements. If you fail to register your vehicle before the emissions test expires, you must retake the test.

How Long Does an Emissions Test Take?

An emissions test itself does not take long. It usually runs between 15 and 30 minutes, depending on your vehicle.

Emissions testing is mandated throughout Ontario, Canada. Vehicles in the region are required to pass a Drive Clean emissions test every two years. The Drive Clean emissions test takes no more than 20 minutes.

What Happens During an Emissions Test?

What happens during an emissions test depends on the type of vehicle you have, the model year and the state. Some tests that may be performed on your vehicle include the following:

  • An on-board diagnostics (OBD) test to check your vehicle’s internal computer, which monitors the engine, transmission and emissions control systems. The OBD test checks if your vehicle’s emissions systems operate properly and within emissions limits.
  • A fuel cap inspection to ensure a tight seal. A loose or missing fuel cap can cause a vehicle to fail an emissions test.
  • A treadmill test, in which the vehicle is placed on rollers and undergoes a road simulation to check emissions.
  • An idling test, to check emissions both while your vehicle idles and with the engine running.

Passing an Emissions Test

Passing an emissions test means that your vehicle meets or exceeds your state’s requirements. You'll find out immediately if you passed or not. Once you pass, you receive a Vehicle Inspection Report that indicates how your vehicle performed. This report gets transmitted directly to the DMV by the testing facility. You also get a copy for your records.

Once you pass an emissions test, you are not required to do another one until notified by the DMV.

Failing an Emissions Test

If your vehicle fails an emissions test, you must make necessary repairs to your vehicle and retake the test. Most states allow you to retake the test at no charge. If your vehicle fails again, you may be eligible for a waiver from the state.


  • A vehicle emissions test takes between 15 and 30 minutes, depending on your vehicle.

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