Missouri’s vehicle emissions regulations aim to reduce pollution from cars and trucks, in line with environmental protection goals and federal air quality standards. These rules primarily apply in specific regions with higher air pollution, so requirements can differ depending on where you live in the state. Understanding these laws helps vehicle owners stay compliant and avoid penalties.
Emissions Testing Requirements
In Missouri, an emissions inspection identifies vehicles that exceed set exhaust emission standards. For most gasoline-powered vehicles made since the 1996 model year, this involves an On-Board Diagnostics (OBDII) test.1Legal Information Institute. 10 CSR 10-5.381 – Onboard Diagnostics Motor Vehicle Emissions Inspection This computerized system monitors engine and emission control performance, and an inspector connects equipment to the vehicle’s OBDII port for the test.
The OBDII test checks the vehicle’s computer for Diagnostic Trouble Codes (DTCs) indicating emission system malfunctions. It also verifies “readiness monitors,” which are self-tests for emission components. To pass, the “check engine” light must be off, and readiness monitors must show completed tests. The number of monitors allowed to be “not ready” can vary by vehicle model year.
The inspection also includes a visual check of components like the catalytic converter; missing or defective parts can cause failure. The fee for an emissions inspection is capped at $24.2Missouri Revisor of Statutes. Section 307.366: Motor Vehicle Emissions Testing, Fees, and Requirements Owners receive a pass or fail report, and a passing inspection is valid for 60 days for vehicle registration or renewal.3Missouri Department of Revenue. Driver Guide – Chapter 14: Vehicle Inspections
Vehicles Subject to Testing
Emissions testing in Missouri depends on vehicle age, weight, and fuel type. Gasoline-powered vehicles (model year 1996 or newer) and diesel-powered vehicles (model year 1997 or newer) require testing.4Gateway VIP. Does My Vehicle Need a Test?
Vehicles with a gross vehicle weight rating (GVWR) of 8,500 pounds or less, like most passenger cars and light-duty trucks, are subject to testing. Heavier vehicles do not require these inspections.
Testing is required every two years, based on vehicle model year: even-numbered model years test in even-numbered calendar years, and odd-numbered in odd years. Vehicles must have a valid emissions inspection to be registered or to renew registration.
Geographic Testing Regions
Missouri’s emissions testing program, known as the Gateway Vehicle Inspection Program (GVIP), is not statewide. It targets specific areas with air quality concerns to meet federal Clean Air Act requirements. The main testing area is the St. Louis metropolitan region, which includes St. Louis City, St. Louis County, Jefferson, and St. Charles counties.5Missouri Revisor of Statutes. Section 643.315: Motor Vehicles Subject to Emissions Program and Affected Areas
The Missouri Department of Natural Resources (DNR) and the Missouri State Highway Patrol jointly manage the GVIP.6Missouri Department of Natural Resources. Frequently Asked Questions – Gateway Vehicle Inspection Program Testing is required for vehicles registered or mainly operated within these designated boundaries.
The need for an emissions test depends on where the vehicle is registered or primarily used, and the Missouri Department of Revenue includes this in the registration process for these zones. The DNR’s GVIP website provides resources, such as a tool to find testing locations.7Gateway VIP. Locate a GVIP Station Near You
Exemptions
Some vehicles and situations qualify for an exemption from Missouri’s emissions testing. These exemptions cover specific vehicle types, their usage, or age.
Vehicles that do not use gasoline or diesel, like electric vehicles, are exempt because they don’t produce tailpipe emissions. Vehicles using other alternative fuels, such as propane or natural gas, might also be exempt under certain conditions.
A vehicle’s age can lead to an exemption. Historic motor vehicles, which are twenty-five years or older, owned as collector’s items, and used mainly for exhibitions and education, are exempt. Owners of these vehicles must obtain historic license plates.
New motor vehicles are exempt for the first four years after their model year if they have fewer than 40,000 miles at their first two-year safety inspection.
If a vehicle has passed an emissions inspection within the last 60 days, it does not need another test if sold during that time. Vehicles driven less than 12,000 miles between two-year safety inspections may qualify for a mileage-based exemption; owners must certify this low mileage during the safety inspection.8Missouri Department of Natural Resources. Mileage-Based Exemption Request Form MO 780-1972
Penalties for Non-Compliance
Not complying with Missouri’s emissions testing rules in designated areas has clear consequences. If a vehicle fails inspection or isn’t tested as required, the Missouri Department of Revenue will not issue or renew its registration.9Gateway VIP. What Should I Know Before the Test? Driving without a valid registration is illegal.
Driving a vehicle that hasn’t met these standards can result in more penalties. If law enforcement finds a vehicle’s registration is invalid due to emissions non-compliance, the driver may face citations, fines, and court costs.
Tampering and Falsification
Missouri law also covers actions taken to bypass the emissions inspection process, like tampering with a vehicle’s emissions controls or faking inspection results.
Tampering means changing, removing, or disabling factory-installed emissions control parts, such as catalytic converters or oxygen sensors. It is illegal to tamper with these systems or to sell a vehicle with tampered devices.10US EPA. Vehicle Emissions Inspection & Maintenance (I/M): General Information for Motorists
Falsification involves creating or using false documents or information for an emissions inspection. This includes a vehicle owner using a fake certificate or an inspector intentionally passing a vehicle that should fail. Inspectors or stations involved in such fraud can have their permits or licenses suspended or revoked. The Missouri State Highway Patrol investigates these cases.