Utah's emissions test requirements and what triggers them

Utah requires an emissions test for most vehicles registered in the state, but the requirement depends on where you live and what you drive. If you live in the Wasatch Front nonattainment area — which includes Salt Lake, Davis, Weber, and Utah counties — you must pass an emissions test every two years before you can renew your registration. If you live outside that area, you do not need an emissions test at all.

Diesel vehicles, motorcycles, and vehicles model year 1967 and older are exempt from the test statewide. Vehicles registered as classic cars or antiques also do not require emissions testing. New vehicles (typically model year 2010 and newer, depending on the specific year) may be exempt for their first few years of registration, though this changes annually.

The test itself measures your vehicle's tailpipe emissions — mainly nitrogen oxides, particulate matter, and hydrocarbons — to confirm they fall within state limits. You cannot renew your registration online or by mail in the Wasatch Front counties without a passing test result first.

Key Takeaways

  • Only vehicles registered in Salt Lake, Davis, Weber, and Utah counties need an emissions test; all other Utah counties do not require one.
  • The test must be completed every two years before registration renewal, and you cannot renew without a passing result.
  • Diesel vehicles, motorcycles, vehicles older than 1967, and registered classic cars are permanently exempt.
  • You can find a testing station through the Utah Division of Air Quality website or by calling your county clerk's office.
  • A failed test does not prevent you from driving, but you must fix the problem and retest before you can renew your registration.

Where to get your emissions test in Utah

The Utah Division of Air Quality maintains a list of certified emissions testing stations on its website. You can search by county or zip code to find stations near you. Most stations are independent repair shops, tire shops, or quick-lube facilities that have been certified to perform the test.

Call ahead before you go. Testing stations have different hours, and some require appointments during busy seasons. Ask whether they can test your specific vehicle type and what payment methods they accept — most charge between $20 and $40 for the test itself.

You will need your vehicle's registration or VIN (vehicle identification number) when you arrive. Bring your driver's license as well. The test takes about 15 to 30 minutes from start to finish.

What happens if your vehicle fails the emissions test

A failed test means your vehicle's emissions exceeded the state limits in one or more categories. The testing station will give you a printed report showing which emissions failed and by how much. This report is yours to keep and use when you take the vehicle to a repair shop.

You do not have to repair the vehicle when ready, and you can drive it while you arrange repairs. However, you cannot renew your registration until you pass the test. If your registration expires before you retest, you are driving with an expired registration, which is a violation.

Take the failed test report to a repair shop and ask them to diagnose the problem. Common causes include a faulty oxygen sensor, a loose gas cap, a malfunctioning catalytic converter, or engine timing issues. Once repairs are complete, return to any certified testing station to retest. There is no limit to how many times you can retest, and you pay the testing fee each time.

Preparing your vehicle for the emissions test

Before you go to the testing station, make sure your vehicle has been driven recently — at least 20 miles in the last few days. A vehicle that has been sitting will not have a warm engine, and the test results may be unreliable. The test is designed to measure emissions from a warmed-up engine.

Check that your gas cap is tight and in good condition. A loose or missing gas cap is one of the most common reasons for test failure and is also the easiest to fix. If your check engine light is on, have the vehicle scanned for diagnostic trouble codes before you test; some codes will cause an automatic failure.

Keep your vehicle well-maintained. Regular oil changes, air filter replacements, and spark plug service help keep emissions low. If your vehicle is older or has high mileage, consider a tune-up before testing if you are concerned about passing.

Registration renewal after a passing emissions test

Once you have a passing test result, you can renew your registration. The testing station will send the result electronically to the Utah Division of Motor Vehicles, or they will give you a printed certificate. If you receive a printed certificate, bring it with you when you renew.

You can renew your registration at your county clerk's office, by mail, or online through the DMV website — but only if your emissions test has passed and the result is in the system. If you are renewing online and the system will not accept your renewal, it usually means the test result has not been received yet. Wait a day or two and try again, or contact your county clerk's office to confirm the result was submitted.

Your registration is valid for two years from the renewal date. Your next emissions test will be due two years later, before you can renew again.

Vehicles that do not need an emissions test

If you live outside the Wasatch Front nonattainment area — in counties like Daggett, Rich, Uintah, Duchesne, Carbon, Emery, Sanpete, Piute, Rich, Sevier, Wayne, Garfield, Kane, or Iron — you do not need an emissions test at all. You can renew your registration without one.

Statewide exemptions include all diesel-powered vehicles, all motorcycles, vehicles manufactured in 1967 or earlier, and vehicles registered as classic or antique vehicles. If your vehicle falls into one of these categories, you will not be asked for an emissions test result when you renew, regardless of where you live.

If you are unsure whether your vehicle is exempt, contact your county clerk's office or the Utah Division of Air Quality. They can confirm your vehicle's status based on its VIN and registration type.

Frequently Asked Questions

Can I renew my registration without an emissions test if I live in the Wasatch Front area?

No. If you live in Salt Lake, Davis, Weber, or Utah counties, you must have a passing emissions test result before the DMV will process your registration renewal. You cannot renew online, by mail, or in person without it.

What if I move out of the Wasatch Front area after my registration expires?

You still need a passing emissions test to renew your registration, even if you have moved to a county that does not require one. The test requirement is based on where your vehicle was registered when the renewal was due. Once you renew in your new county, future renewals may not require a test, depending on your new location.

How long does a passing emissions test result stay valid?

A passing result is valid for two years from the test date. You must retest before your registration renewal date, which is two years from your last renewal. If you retest early, the new result replaces the old one.

What should I do if the testing station says my vehicle cannot be tested?

Some vehicles — such as those with custom engines, significant modifications, or missing emissions equipment — may not be testable at a standard station. Ask the station for a referral to a shop that handles problem vehicles, or contact the Utah Division of Air Quality for guidance on your specific situation.

Can I test my vehicle before my registration renewal is due?

Yes. You can test early, and the result will be valid for two years from the test date. This is useful if you want to renew your registration early or if you are concerned about passing and want to address problems ahead of time.