car getting emissions test at mechanic shop

If you own a car in Utah, chances are you’re familiar with the process of emissions testing. But why do vehicles have to pass emissions tests? There are some guidelines for getting your vehicle tested based on its model year, and Master Muffler Downtown SLC shares those details and more below.

What Are Emissions?

Emissions from vehicles are composed of a variety of pollutants, including carbon dioxide, nitrogen oxides, hydrocarbons, and particulate matter. These pollutants are released into the atmosphere when a vehicle is operated, and they can have a negative impact on air quality.

Why Do Vehicles Have to Pass Emissions Tests?

To protect air quality, many states require that vehicles undergo regular emissions testing. Emissions tests help ensure that vehicles are not releasing excessive amounts of pollutants into the atmosphere. 

Pollutants Emitted by Vehicles

The greenhouse gasses emitted by vehicles include:

  • Nitrogen Dioxide
  • Carbon Monoxide
  • Hydrocarbons
  • Benzene
  • Formaldehyde

A properly working exhaust system converts some of these pollutants to less harmful gasses, such as:

  • Water Vapor
  • Carbon Dioxide
  • Nitrogen Gas

Ideally, a catalytic converter converts over 90% of the vehicle’s pollutants into less harmful emissions.

More About the Catalytic Converter

The exhaust system is responsible for trapping pollutants before they’re emitted into the atmosphere. The catalytic converter could be considered the powerhouse of the exhaust system since it turns toxic pollutants into much less harmful gasses and vapors.

Inside a catalytic converter, there’s a chamber that initiates a chemical reaction. Toxic molecule compounds are broken up to change their makeup. The resulting molecular structures are much safer than what entered the chamber in the first place.


Vehicles have either a reduction catalyst or an oxidation catalyst composed of the following:

  • Platinum, Palladium, Rhodium
  • Ceramic Honeycomb Chamber
  • Oxygen Sensor

How Can You Ensure Your Vehicle Passes Regular Emissions Tests?

There are a few things you can do to help ensure your vehicle passes regular emissions tests. First, make sure to have your vehicle regularly serviced and maintained. Routine oil changes and tune-ups can help keep your vehicle’s emission control system in good working order. 

Additionally, avoid using leaded gasoline, and keep your tires properly inflated by referring to the recommended PSI in your vehicle’s owner’s manual.

If you’ve recently had some work done on your vehicle to help it pass, make sure you “warm up” the engine before your test. Going for a drive on the Interstate for 20 minutes or so can give the exhaust system a chance to go through a full cycle.

If your car won’t pass, Master Muffler can run a diagnostic test to see if any engine codes relate to the exhaust’s performance so we can identify the problem.

Vehicle Inspections in Utah

As of 2018, Utah made some updates to the safety and emissions testing schedules required of vehicles. In Salt Lake County, the Department of Motor Vehicles states:

Vehicles registered in Salt Lake County with model years less than six years old are required to have an emission test once every two years. Vehicles in this category that have even-numbered model years must have an emission test in even-numbered years, and vehicles that have odd-numbered model years must have an emission test in odd-numbered years.”

If your vehicle doesn’t pass, you can schedule a retest once you’ve had repairs completed. If your vehicle repeatedly fails, you can contact your county emissions office and see what your options are for obtaining an inspection waiver.

Who Performs Emissions Testing on Vehicles?

Emissions testing is typically performed by certified technicians at licensed testing facilities. Master Muffler Downtown is one such facility you can bring your vehicle when it’s time to test. We can also renew and print your registration on-site and provide you with stickers for your license plate if we have them in stock. 


(801) 305-3049

Whether you’d like to get in for an emissions test or want to schedule repairs or a tune-up, contact Master Muffler Downtown Salt Lake City today. We can help improve the performance of your vehicle’s exhaust system so it keeps you, and other motorists, safer on the road. If you need to run diagnostics to see what’s wrong with your exhaust system, we can help with that as well. 


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