Emissions Testing in Mississippi

Who Needs an Emissions Test or Smog Check

In most of Mississippi, no vehicle needs an emissions test. However, emissions testing requirements in Mississippi may apply in limited areas that do not meet federal air quality standards. In those areas, gasoline passenger vehicles and light duty trucks of certain model years may be subject to testing under federal Clean Air Act rules. Exemptions often include older vehicles, electric vehicles, and certain specialty vehicles.

How Often Tests Are Required

Statewide, emissions testing is not required. In limited areas where testing applies, it may be tied to vehicle registration cycles. Specific frequencies depend on local requirements. Always check local authority guidance as rules and schedules may vary and could change.

Where Emissions Testing Is Required

Except for a few jurisdictions that may require testing to meet air quality mandates, most of Mississippi does not enforce emissions testing. Areas that historically failed to meet federal air standards may impose testing requirements on vehicles at registration renewal. Otherwise, testing is not enforced. Requirements depend on local air quality zones.

What Happens During the Test

In areas where an emissions test applies, the process is similar to tests in other states. A technician will connect to the vehicle’s onboard diagnostic (OBD‑II) system to check for emission‑related fault codes. They may perform a visual inspection of emissions equipment. Tailpipe testing is less common but may be required in some cases. Readiness monitors are checked. If a fault code is present or monitors are incomplete, the vehicle may fail.

Areas in Mississippi That Require Emissions Testing

Requirements differ across the state depending on local air quality planning zones. Most areas of Mississippi do not require emissions testing so listings are voluntary. In a few cities such as Biloxi, Oxford, Pascagoula, or Vicksburg, test options may exist even if not required to help vehicle owners confirm emissions control systems are working properly. This directory shows emissions testing locations in Mississippi including those in these cities. Urban centers may have more testing services due to higher population density and demand, even when testing is not mandated.

How the Emissions Test Works in Mississippi

When an emissions test is required or sought voluntarily, the process usually takes fifteen to thirty minutes. Vehicle owners should bring proof of registration and a form of identification. At the station, the vehicle connects to the OBD‑II port if equipped. The technician reviews fault codes and readiness status, inspects emissions‑related components, and may conduct a tailpipe check in rare cases. Common failure causes include a lit check engine light, incomplete readiness monitors, or malfunctioning emissions systems. If the vehicle fails, repairs are needed and the test must be repeated. Costs vary by station. Passing results in a certificate or report to use for registration if required.