Texas Vehicle Emissions Testing: Which Counties Require It?

Yes, emissions testing is mandatory in Texas—but only in 17 designated counties (mostly major metro areas) as part of the annual safety inspection. If you live in these counties, your vehicle must pass an emissions test every two years (gasoline vehicles 2-24 model years old).

Counties With Emissions Programs (I/M Areas)

• Houston-Galveston-Brazoria: Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, Waller
• Dallas-Fort Worth: Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, Tarrant
• El Paso: El Paso County (not listed in source but part of program)
• Austin-Round Rock: Travis, Williamson (not listed in source but part of program)

Note: The source lists 17 counties; current TXDPS program includes 17 core counties. Always verify with Texas DPS for your specific county.

Key Exemptions

• Vehicles 25+ model years old (classic/antique)
• Vehicles with GVWR > 10,000 lbs (heavy duty)
• Diesel vehicles (different testing)
• Motorcycles, trailers
• New vehicles (first 2 model years)

What's Tested

OBD-II scan (1996+), tailpipe (older), gas cap pressure, visual inspection of emissions components. Fail = repair & retest. Waivers available for costly repairs.