What You Need to Know About Emissions Testing in Texas

Texas emissions testing is required annually for any gasoline vehicles between 2 to 24 model years old—but only in specific counties throughout the state.
Written by Claire Beaney
In certain Texas counties, emissions testing is required annually for any gasoline vehicles between 2–24 model years old.
  • To set up an emissions test for your motor vehicle, find a testing center near you, show up for your vehicle inspection, and pay the necessary fee.
  • You won’t pay more than $31.50 combined for your safety inspection and emissions test, although the exact amount will depend on your testing area and vehicle details.
  • If your vehicle fails its emissions test, you’ll need to address any necessary repairs and have it re-tested before you can register it.

Texas emissions testing regulations

Texas is one of the states that require vehicles to get emissions tests. The Texas Department of Public Safety (DPS), working alongside the Texas Commission on Environment Quality (TCEQ), first began vehicle emissions testing in 2002 to help improve air quality across the state.
But in Texas, not every car needs to have its emissions checked. Here’s how to determine whether or not you are exempt.

Which counties in Texas require emissions testing?

Location makes a difference: Because
Texas' emissions inspection program
is regional, you may not have to do an emissions test at all depending on where you live and drive.
If your vehicle is registered in one of the counties listed below, you are inside the assessment region and must pass an emissions test before you can register your vehicle:

Which cars need emissions testing in Texas?

If you own a gasoline vehicle between 2 to 24 model years old, you must pass an emissions test annually.
Exemptions from Texas emissions testing:
  • Vehicles made in the last 2 model years
  • Vehicles made over 24 years ago
  • Diesel vehicles
Keep in mind: In Texas, all cars and trucks must pass an annual safety inspection ahead of vehicle registration, regardless of what county you live in. Hybrid cars also have to go through a smog check.

How does Texas emissions testing work?

If your car needs to be tested, here's the process you’ll need to follow:
  1. Locate a testing center. You can use the
    DPS website
    to find an inspection station near you where you can get an emissions test done.
  2. Bring your vehicle in for the inspection. During inspection, the inspector will examine the various components of your emissions system, including its catalytic converter, oxygen sensors, muffler, and more. Depending on how old your car is, how it runs, and what kind of fuel it uses, you may be able to take different types of tests (more on that below). 
  3. Pay the necessary fee. Fees are indicated above, but depending on the age of your car, you should anticipate spending between $12 and $25.
Keep in mind: Texas caps smog check fees between $11.50 and $24.50 for TSI, ASM, or OBD inspections, based on the
testing location
. The total for both a safety inspection and emissions test cannot exceed $31.50, depending on the required testing area, vehicle year, and engine type.

Types of emissions tests

A normal emissions test will include a basic check to confirm that your vehicle is safe to inspect, along with a visual inspection of your dashboard lights and gas cap. The rest of the examination, however, is dependent on the type of vehicle you drive.
  • OBD inspection: Vehicles manufactured in 1996 or later model years, including hybrids, must undergo an on-board diagnostics (OBD) inspection. The technician will use an OBD-II scanner to look for trouble codes related to emissions issues.
  • Acceleration simulation mode (ASM) test: This is sometimes called a “treadmill test”. It entails placing the vehicle on a large treadmill for around four minutes to simulate how it runs on the road.
  • Two-speed idle test: In this test, technicians insert a probe into the exhaust pipe and measure the engine speed with a tachometer. Then, as the name implies, they'll let the engine idle twice before revving it to 2500 RPM. 
Pro tip: Before bringing your vehicle in for its emissions test, be sure to address any obvious problems with your emissions system, such as your check engine light remaining on—otherwise, you won’t pass inspection.

What happens if you fail emissions testing in Texas?

If a vehicle fails an emissions inspection, any emissions-related repairs must be completed by a licensed mechanic at a designated repair facility, and the vehicle must be retested before you can hit the road.
Texas also offers waivers and extensions to eligible car owners—you can see the list
Keep in mind: If the technician observes any visible smoke, missing or modified equipment, or a failing gas cap, the waiver request might be denied.
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