Vehicle Emissions
Your car needs an emissions test every year in Rockwall County
Rockwall County is in the Dallas-Fort Worth emissions testing area, so most gasoline-powered vehicles registered here must pass an annual emissions inspection to renew registration.
Texas uses a program called Two Steps, One Sticker. Step one is your vehicle inspection. Step two is emissions testing (required in Rockwall County). Both must be done before you can renew your registration and get your sticker. Enhanced emissions testing began in Rockwall County on May 1, 2003.
The emissions test applies to gasoline vehicles from the second through the 24th model year. Electric vehicles, diesel vehicles, motorcycles, and mopeds are not required to pass an emissions inspection. If you move to Rockwall County from a county that does not require emissions testing, factor in this annual requirement.
Source to confirm: TCEQ — Vehicle Emissions Inspections in Texas