What if You Fail the Texas Emissions Test?

What Does the Texas Emissions Test Assess?

  1. Two-speed Tailpipe Testing - For year models 1995 and older
  2. On-Board Diagnostics (OBD-II) - For year models 1996 and newer
Two-speed Tailpipe Testing

The two-speed tailpipe test is performed for vehicles manufactured in 1995 and prior. These vehicles do not come with the on-board diagnostic system found on all cars manufactured in 1996 and later.

The testing involves measuring tailpipe emissions while the vehicle idles at low and high speeds. Vehicles fail the two-speed tailpipe test when emitting high amounts of carbon monoxide and/or hydrocarbons.

On-Board Diagnostics (OBD-II)

The OBD-II test involves plugging a scan tool into the vehicle’s internal computer. The OBD-II scanner then analyzes computer data to determine whether the emissions system works well. Specifically, the OBD-II test checks the following vehicle components:

Bulb Check

Before plugging in the OBD-II scanner, the inspector checks the operability of the following indicators and lights:

  • Malfunction Indicator Lamp (MIL)
  • Service Engine Soon Light
  • Check Engine Light
  • Check Engine Symbol

These indicators must light up when the ignition is turned to the “ON” position and must switch off upon engine start. If the indicators fail to light up, the vehicle will fail the inspection.

Maintenance Indication Light (MIL) Command Status and Diagnostic Trouble Code Check

With the scanner plugged into the vehicle’s internal computer, the inspector checks the following:

  • Maintenance Indication Light (MIL) Command Status
  • Diagnostic Trouble Codes (DTCs)

The vehicle will fail the inspection if the MIL command status is ON and a DTC is set. Otherwise, the inspector will proceed with the third check.

Readiness Monitors Check

The test technician checks the vehicle’s engine and emissions systems for any monitors with a “Not Ready” status.

The 17 counties mandating emissions inspections are located around major metropolitan regions, excluding San Antonio. These counties are: Harris, Fort Bend, Brazoria, Montgomery, Galveston, Williamson, Travis, Dallas, Tarrant, Denton, Collin, Rockwall, Kaufman, Ellis, Johnson, Parker, and El Paso.

Texas Emissions Testing Waivers, Extensions, and Exemptions

There are special conditions that allow vehicles registered in listed counties to forego emissions testing. They may undergo testing at counties not on the list by submitting an exemption affidavit and if any of the following conditions are true:

  • The vehicle will not be driven, parked, or stored for less than 60 days per year in the counties listed above. (e.g., company fleet, hunting, and recreational vehicles.)
  • The vehicle will no longer be used in any of the counties listed above. (e.g., vehicle owner moved from a listed county.)
  • The vehicle will not return to the county listed above during the current vehicle registration sticker’s validity.
Waivers and Extensions
  • Parts Availability Time Extension: Issued when a vehicle fails the emission inspection due to an unavailable vehicle part, thus impeding repairs.
  • Low-Income Time Extension: A one-year extension issued to vehicle owners whose annual income is below that of the national poverty level. It is valid only for one inspection cycle but may be granted more than once across a vehicle’s lifespan.
  • Low Mileage Waiver: Issued to vehicle owners whose emission-related repairs cost at least $100 but still fail both the initial inspection and re-inspection. The vehicle in question must have been driven less than 5,000 miles in the previous inspection cycle and is expected to be driven less than 5,000 miles at the time of the next inspection.
  • Individual Vehicle Waiver: Available to vehicle owners whose emission-related repairs cost them at least $600 ($450 in El Paso) and still fail the emissions inspection or are unable to qualify for another type of waiver. The Individual Vehicle Waiver may be granted provided the granting of the same will not have a significant adverse impact on air quality.

Note: When applying for a waiver, all repair-related receipts must be presented to a Department representative at a local DPS waiver/challenge station.

What if You Fail the Emissions Inspection?

The most common conditions that cause vehicles to fail Texas emissions inspections are:

  • Catalytic converter failure
  • Faulty gas cap
  • Fuel metering is not up to specification
  • Incorrect ignition timing
  • Inoperative injection system
  • Faulty thermostatic air cleaner
  • Misrouted vacuum line
  • Faulty Positive Crankcase Ventilation (PCV) System
  • Defective Exhaust Gas Recirculation (EGR) System

Final Words

Scroll to Top