Do You Need an Emissions Test in Missouri? Costs and Exemptions

An emissions test in Missouri is required only if your vehicle is registered in St. Louis City, St. Louis County, St. Charles County, or Jefferson County.¹ Registered anywhere else in the state? You don’t need one. Even inside those four areas, plenty of vehicles are exempt. When the test does apply, it costs $24, takes a few minutes, and you need a passing result before the Department of Revenue will renew your registration.

Who Needs the Test

The Gateway Vehicle Inspection Program (GVIP) runs emissions testing in the St. Louis area. Your vehicle needs a test if all three of these are true: it’s registered in one of the four covered counties, it’s a gasoline vehicle from model year 1996 or newer (or a diesel from 1997 or newer), and it weighs 8,500 pounds or less.²

Testing runs on a two-year cycle tied to model year. Even-numbered model years test in even calendar years; odd-numbered model years test in odd calendar years.³

Vehicles That Are Exempt

Even inside the four covered counties, several categories skip the test:

New and unused vehicles from the current model year or within two calendar years of it, if the odometer reads under 6,000 miles at the original sale.³
Vehicles that haven’t been titled or registered, for four model years after manufacture, if the odometer reads under 40,000 miles at the first required biennial safety inspection. You submit a Mileage-Based Exemption Request to the Department of Natural Resources.¹
Gasoline vehicles from model year 1995 or older.¹
Diesel vehicles from model year 1996 or older.¹
Vehicles more than 25 years old owned as collector’s items and used for exhibition or educational purposes, once they carry historic plates.²
Vehicles four years old or older driven fewer than 12,000 miles between biennial safety inspections. This also requires a Mileage-Based Exemption Request, plus previous and current safety inspection records to confirm the mileage.¹
Motorcycles, motortricycles, autocycles, and dirt bikes.¹
Anything with a manufacturer’s gross vehicle weight rating over 8,500 pounds, including RVs above that threshold.¹
Vehicles powered exclusively by electricity, solar power, hydrogen, or fuels other than gasoline, diesel, or ethanol blends, including plug-in electric vehicles.¹

Emissions Test vs. Safety Inspection

These are two different requirements, and people mix them up constantly. Missouri requires a safety inspection every two years for most vehicles statewide, regardless of where they’re registered. The emissions test is an additional requirement that applies only in the four St. Louis-area counties.²

If your vehicle is exempt from emissions testing, you still need a valid safety inspection. If you need both, you need passing results for each before the Department of Revenue will renew your registration.⁴

What the Test Involves

The test itself is short. An inspector connects a cable to the OBD-II port on the driver’s side of your vehicle. The inspector’s computer talks to your vehicle’s onboard computer to confirm that emissions-control devices and engine components are functioning properly. Every emissions-related part needs to be working for the vehicle to pass.⁵

This OBD-II method covers all gasoline vehicles from 1996 onward and all diesel vehicles from 1997 onward, which is the full population of vehicles the program currently tests.⁵

You can find authorized inspection stations through the Missouri State Highway Patrol’s online mapping tool, which lets you search by city or zip code.⁶

What It Costs

The test fee is $24.⁷ If your vehicle fails and you get it repaired, the retest is free as long as you return to the same station within 20 business days. After that, you pay the full $24 again.⁸

If Your Vehicle Fails

A failed test generates a Vehicle Inspection Report listing what went wrong. You make the repairs, then bring the vehicle back. Your best window is that free retest: 20 business days at the same station where you originally tested.⁸

Cost-Based Waivers

If your vehicle still can’t pass after repairs, you may qualify for a waiver that lets you register anyway. The threshold depends on who did the work:

Repairs by a technician: at least $450 in qualified emissions-related repairs. Labor counts toward the threshold only if performed by a Missouri Recognized Repair Technician (MRRT).⁹
Self-repairs: at least $400 in qualified parts.⁹
Disability or public assistance recipients: if you’re the titled owner and rely solely on state or federal disability benefits or other public assistance, the threshold drops to $200.⁹

Estimate-Based Waivers

If a diagnosed problem would cost more than $450 in parts and labor (labor counted only from an MRRT), you can apply for a waiver based on the estimate alone, without completing the repair.⁹ This is the escape hatch when a repair costs more than the vehicle is worth.

Buying or Selling a Vehicle in an Emissions County

Sales inside the four covered counties come with their own rules, and who’s responsible for the test depends on whether the seller is a dealer or a private party.

Dealer Sales

Dealers must sell vehicles that pass emissions. A dealer can use a compliance certificate issued up to 120 days before the sale, and they hand that certificate to you for registration. Register within 120 days of the certificate date or you’ll need a new test.¹⁰

A dealer can also sell a vehicle without a valid certificate, but only if they disclose that in writing on both the bill of sale and the purchase contract. You then have 10 days and no more than 1,000 additional miles to test the vehicle. If it fails, the dealer must repair it at no cost to you. Miss that window and the repair bill becomes yours.¹⁰

Vehicles sold with junk, salvage, or rebuild titles, and vehicles bought at public auction, don’t get those dealer protections. Buy through any of those channels and you’re on the hook for repairs.¹⁰

Private Sales

Private sellers are required to provide the buyer with a current emissions approval or waiver before the sale. The buyer then has 60 days from the date of the emissions test to use that certificate for registration.¹⁰ If someone tries to sell you a car in an emissions county without a passing certificate, treat that as a warning sign.

Renewing Your Registration

A valid emissions certificate is required before the Department of Revenue will renew your registration, and it can’t be more than 60 days old when you renew.⁴ Inspection stations submit passing results electronically, so the Department of Revenue already has the result by the time you renew online or in person.

Without a passing result or an approved waiver, the Department of Revenue will deny your renewal. Driving on expired registration because you haven’t passed emissions is a class C misdemeanor under Missouri law, which carries up to 15 days in jail.³¹¹

If you’re a Missouri resident temporarily living out of state, or military personnel stationed elsewhere, you can renew without an emissions inspection by marking the box on your renewal application indicating the vehicle has been out of state for more than 60 days.⁴

1
Missouri Department of Revenue. Motor Vehicle – Additional Help Resource
2
Gateway Vehicle Inspection Program (GVIP). Does My Vehicle Need a Test?
3
Missouri Revisor of Statutes. Revised Statutes of Missouri, RSMo Section 307.366
4
Missouri Department of Revenue. Renewing Missouri License Plates
5
Gateway Vehicle Inspection Program (GVIP). Emissions Testing Procedure
6
Missouri State Highway Patrol. Station Locations
7
Missouri House of Representatives Document Tracking. Fiscal Note L.R. No. 4654H.01P Bill No. Perfected HB 2189
8
Gateway Vehicle Inspection Program (GVIP). Vehicle Failed Emissions Test
9
Gateway Vehicle Inspection Program (GVIP). Forms, Waivers and Extensions
10
Gateway Vehicle Inspection Program (GVIP). Buying Vehicles from a Dealer or Private Individual
11
Missouri Revisor of Statutes. Revised Statutes of Missouri, RSMo Section 558.011