Most gasoline, hybrid and light diesel vehicles registered inside the Portland testing boundary need a passing DEQ emissions test before registration can be renewed. The test costs $25 and is charged only on a pass. The most common cause of a failed visit is a lit check engine light or an “Unready” result, and both can be handled before the trip. Integrity Auto, an independent Portland-area shop for Toyota, Lexus, Subaru and Honda vehicles, offers check engine light and DEQ diagnosis, plus emission testing and repairs, for owners who want that sorted out first.

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TL;DR

  • Vehicles of model year 1975 and newer, registered inside the Portland boundary, must test every two years, unless they are exempt (newer model years, electric vehicles, motorcycles and others).
  • The fee is $25 in the Portland area, due only after a pass. A failed test costs nothing.
  • A lit check engine light means a fail in nearly every case. An “Unready” result means the car needs more driving before retesting.
  • Testing happens at a DEQ Clean Air Station or, for eligible vehicles, through DEQ Too at a participating business, which may add its own service fee.
  • Repairs and drive cycles done before the test prevent a second trip.

Who has to test in Multnomah County

Oregon DEQ runs a biennial vehicle emissions testing program in the Portland and Medford areas. A vehicle registered within a testing boundary must pass before the Oregon DMV will renew its registration. The boundary covers parts of Multnomah, Clackamas and Washington counties, so the registration address decides it. The DMV renewal notice says whether a test is required.

Per DEQ, all 1975 and newer gasoline, alternative-fuel and hybrid vehicles in the boundary must be tested. The same applies to 1975 and newer diesel vehicles with a gross vehicle weight rating (the maximum loaded weight set by the manufacturer) of 8,500 pounds or less. Diesel cars and light diesel trucks are therefore included.

Exempt vehicles

The same DEQ page lists these exemptions:

  • newer model year vehicles
  • vehicles legally registered outside the boundary
  • heavy-duty diesel vehicles
  • motorcycles
  • low-speed vehicles
  • fully electric vehicles

DEQ explains that newer model years are exempt because they typically have lower mileage and fewer emissions problems. For 2026, DEQ lists model years 2023 (if the current registration expires before January 1, 2027), 2024, 2025, 2026 and 2027 as exempt. The exemption window moves forward each calendar year, so the DEQ page is the place to confirm the current years. Federal approval of Oregon’s program updates, effective May 4, 2026, made explicit that new vehicles are exempt until January 1 of the fourth calendar year after their model year.

Owners of much older cars sometimes look at historic plate eligibility rules, which involve more than a vehicle’s age.

What the test checks

For 1996 and newer gasoline vehicles up to 8,500 pounds, and 1997 and newer light diesels, DEQ reads the on-board diagnostics (OBD) system, the computer that monitors emissions equipment. Two results cause most failures:

  1. Check engine light on. The OBD system has detected an emissions-related fault, and the vehicle will not pass.
  2. “Unready” status. The self-check monitors have not finished running, often because the battery was disconnected or codes were recently cleared. The car must be driven further before it can be tested.

DEQ’s own guidance says a lit check engine light on a 1996 or newer vehicle fails in the vast majority of cases. After a repair, the mechanic should explain which drive cycles (specific driving patterns that let the monitors finish) are needed before retesting. Integrity Auto has guides on what causes a car to fail an emissions test and on avoiding an Unready result with drive cycles.

Cost: $25, charged only on a pass

The Portland-area testing fee is $25. It is due only after the vehicle passes and receives a Certificate of Compliance. A failed test carries no charge, so a retest after repairs does not add a second DEQ test fee.

DEQ Too uses the same $25 fee in the Portland area. Some DEQ Too locations add a device-usage or service fee. DEQ states that the business sets this fee, not DEQ, and none of it goes to DEQ. The total at a DEQ Too location can therefore be higher than at a Clean Air Station, and the amount should be confirmed there before the test.

Cost: $25, charged only on a pass

Where to test

Clean Air Stations

DEQ operates six Clean Air Stations in the Portland area, including Northeast Portland (7701 NE 33rd Drive), Gresham, Clackamas, Sherwood and Sunset. The Portland-area stations are generally open Tuesday, Thursday and Friday from 8:30 a.m. to 5:30 p.m., Wednesday until 7 p.m., and Saturday from 8:30 a.m. to 1 p.m., per DEQ’s locations and hours page. They are closed Sunday, Monday and holidays. The same page notes that afternoons and later in the week tend to be quieter, while Saturdays and the first and last week of the month tend to be busier. Holiday closures and schedule changes are posted there.

A driver should bring the entire DMV renewal form with section 1 (insurance information) and section 2 (owner’s signature) completed. DEQ accepts cash, PIN-less debit or credit cards (Visa, MasterCard, Discover) or a money order. A passing vehicle can receive its renewal tags at the station.

Clean Air Stations

DEQ Too

DEQ Too is a remote option: a telematics device plugged into the OBD port sends data to DEQ, which issues the pass or fail result. It is available at more than 200 repair shops, dealerships and other businesses in the Portland and Medford areas. Eligibility requires:

  • registration inside the boundary with a current renewal (not expired more than 365 days)
  • a vehicle at least four model years old
  • an electronic VIN, typically 2005 and newer
  • a standard passenger plate
  • willingness to complete DEQ certification and DMV renewal online

It applies only to renewals, not to vehicles new to Oregon or title transfers. The process has three steps: check results at DEQToo.org with the plate or VIN and mileage, pay for the Clean Air Certificate of Compliance online, then renew through the DMV online system. Stickers can arrive in as few as three business days.

How to avoid a second trip

A pass is more likely when the car is ready before it reaches the test lane.

  1. Check the dashboard. If the check engine light is on, diagnosis and repair come first. A code reader shows the stored fault, but the cause still needs to be found and fixed.
  2. Repair the cause, not only the code. Clearing codes resets the monitors and produces an Unready result. Integrity Auto explains the monitor rules and fixes in a separate guide.
  3. Complete the drive cycles. After repairs or a battery replacement, the car needs enough mixed driving for the monitors to finish before testing.
  4. Allow time. The certificate is valid for 180 days, so testing early leaves room for repairs. Once used for registration, the vehicle does not need to test again for two years.

Emissions diagnosis and repair for Toyota, Lexus, Subaru and Honda

Integrity Auto is an independent shop for Toyota, Lexus, Subaru and Honda vehicles in the Portland, Oregon area. Its listed services include check engine light and DEQ diagnosis, emission testing and repairs, and complimentary multipoint inspections. Its technicians are ASE certified, and the shop uses OEM parts and offers longer warranties than dealership repairs, according to the company. For a vehicle with a lit check engine light, the DEQ emissions help page describes the process, and the diagnosis page explains diagnostic charges and estimates.

Integrity Auto

Brand-specific service is also listed for Toyota, Lexus, Honda and Subaru. Owners can start from the Integrity Auto home page to schedule emission testing and repairs.

FAQ

Does Portland require emissions testing?

Yes, for vehicles registered inside the Portland testing boundary, which includes parts of Multnomah, Clackamas and Washington counties. The DMV renewal notice states whether a test is required for a given address. Exempt vehicles include electric vehicles, motorcycles and the newest model years.

Do diesel cars have to go through DEQ in Oregon?

Light diesel vehicles of model year 1975 and newer with a gross vehicle weight rating of 8,500 pounds or less must test if registered inside the boundary. Heavy-duty diesels are exempt. A driver of a diesel that qualifies for the exemption but still receives a renewal notice can visit a Clean Air Station for assistance.

How much does an emissions test cost in Oregon?

In the Portland area the fee is $25, due only after a passing result. A failed test is free. In the Medford area it is $20. DEQ Too locations may add their own device or service fee.

What happens if the car fails?

The car must be repaired and retested. No DEQ fee is charged for the failed test. A lit check engine light is the most common reason, and after repair the drive cycles must be completed so the car does not show as Unready.

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