A standard car emissions test typically takes 20 to 30 minutes from the time you pull into the inspection station. However, the actual time your car is on the testing equipment is much shorter, often just 5 to 10 minutes. The total duration depends heavily on the testing method used by your state and the wait time at the facility.
The two most common types of emissions tests are the Two-Speed Idle (TSI) test and the On-Board Diagnostics (OBD-II) test. The OBD-II test is faster and more common; a technician simply plugs a scanner into your car's OBD-II port (usually under the dashboard) to read the vehicle's computer for emissions-related fault codes. This process is quick and non-intrusive. The older TSI test, which involves placing a probe in the tailpipe while the engine idles and revs, takes a bit longer.
Several factors can influence your total wait:
- Time of Day/Month: Lines are longest on weekends and near the end of the month when registrations are due.
- Test Result: A passing result is quick. A failure may require a longer diagnostic check to identify the issue.
- Vehicle Readiness: If your car's computer isn't "ready" for the OBD-II test (e.g., because the battery was recently disconnected), you may be turned away and need to drive the car for a specific drive cycle before returning.
To save time, schedule an appointment if possible, avoid peak hours, and ensure your check engine light is off. Bringing the required documents, like your vehicle registration, will also streamline the process.
| Test Type | Typical Testing Duration | Common States Using This Method | Key Factor Affecting Time |
|---|
| OBD-II Scan | 5 - 10 minutes | CA, NY, PA, IL, MA | Wait time at station |
| Two-Speed Idle (TSI) | 10 - 15 minutes | Some areas of AZ, GA, WI | Complexity of the test procedure |
| Acceleration Simulation Mode (ASM) | 10 - 20 minutes | Some localized programs | Vehicle's ability to pass quickly |
| Dynamometer Test | 15 - 20 minutes | CO, NC (for certain older models) | Setup and calibration time |
