Utah Emissions Inspections

All vehicles registered in Utah with model years six years old and greater that have even-numbered model years, must have an emission test in even number years, and vehicles with odd-numbered model years must have an emission test in odd-numbered years. Vehicles with model years 1968 or older do not require an emission test.

In general, Utah State Law requires Emissions tests every 2 years for vehicles less than 6 years old. Failure to ensure proper emissions not only creates more undue Utah smog and delays your vehicle registration, but can cause a need for costly auto repair in the future.

2021 Emission Inspection Requirements

tailpipes on a car

  • 2021 not required
  • 2020 not required
  • 2019 required
  • 2018 not required
  • 2017 required
  • 2016 not required
  • 2015 to 1968 required in 2021
  • 1968 and older not required


  • New vehicles with an MSO
  • Any vehicle with a model year 1967 & older
  • Any diesel vehicle with a model year 1997 & older and with a GVWR less than 14,000 lbs.
  • All implements of husbandry
  • Off-highway vehicles
  • Electric vehicles
  • Motorcycles or motor-driven cycles
  • Farm vehicles
  • Vintage or custom vehicles
  • Maintenance or construction vehicles not designed or licensed to operate on a highway
  • Military tactile vehicles


Come into South Orem Master Muffler and we’ll take care of that for you.

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Signs To Watch For

If your check engine light is on, your car will not pass inspection. Before doing any testing, any issues involving the check engine light must be addressed. If your check engine light is on, our full-service shop can quickly diagnose the problem and repair it for you, before performing the state inspection.

Steps to Improve Emissions

  • Oxygen Sensor: Your vehicle’s oxygen sensor is what helps the onboard computer system create the proper fuel-to-air ratio. When this sensor is broken, the alignment of fuel and air will be wrong, which will drastically increase the emissions.
  • Air Injector: If any component in your air injector is broken or misaligned, it reduces your car’s ability to use outside air in the fuel supply, which means that the emissions aren’t being “watered down.”
  • Catalytic Converter: This device is critical for breaking down and turning the harmful emissions gases, such as nitrogen, hydrocarbon, and carbon monoxide, into gases that are far less harmful. A bad catalytic converter can more than double your emissions.
  • EGR: Also known as “exhaust gas recirculation”, the EGR is a device that controls the exhaust gases in your vehicle so that they don’t create oxides in the nitrogen formation, which is one thing that causes harmful emissions.

How You Can Reduce Your Emissions

While a mechanic is important to make sure your car is emitting less particulate matter, there are actually steps you can do to improve your emissions on the road.

  • Keeping up on your regular oil changes.
  • Putting gasoline additives in your car to keep the engine clean.
  • Using high-quality gasoline. Get the premium-grade option if you can.
  • Make sure that your tires have a proper inflation level. Poorly inflated tires reduce your fuel efficiency, which causes more emissions.

The Finest Auto Care at Tunex Orem

Here At Tunex Orem, we’ll make sure that your emissions are done correctly. If there are any issues with your vehicle we can work them for you or refer you to someone who can. We’ll also be able to let you know if there are any issues that you should be aware of in the near future. We are your Orem auto repair experts!

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