Vehicle Inspection

Oregon DEQ Vehicle Test Methods

Tailpipe emissions test 

(1995 and older model years)
At a Clean Air Station, a DEQ inspector places a probe into the vehicle’s tailpipe to ensure vehicle emissions are not exceeding standards.

On-board diagnostics test 

(1996 through current model years)
The vast majority of vehicles receive this test. At a Clean Air Station, a DEQ inspector uses a plug-in cable to transmit data between the vehicle’s on-board diagnostics (OBD) computer and DEQ’s computer to ensure that pollution control equipment is working properly.

Testing at dealership locations 

(1996 through current model years)
Instead of an auto dealership shuttling their vehicles one-by-one to DEQ, DEQ comes to the dealer’s location to test their multiple vehicles. Dealerships sign up and make appointments with M.O.S.T. (Mobile On Site Testing).

Self-Service test 

(1996 through current model years)
At self-service kiosks, motorists use a DEQ touch-screen computer and cable to plug-in to their own vehicles’ on-board computer. This option is currently in use at most Clean Air Stations.

DEQ Too™ 

(2005 through current model years)
The DEQ Too™ (or “Remote OBD”) test option uses telematics devices to transmit OBD data without the motorist visiting a Clean Air Station. This is a new test method that will become more and more available over time. Learn more about this new test method.

DEQ conducted trials of test methods prior to implementation


For questions or feedback on the Vehicle Inspection Program, visit our Questions and Comments page, or call one of our area contact numbers below:

  • Portland Area: 503-229-5066
  • Medford Area: 541-776-6145
  • Toll-Free in Oregon: 877-476-0583
  • Hearing Impaired: 711