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Diesel Retrofit Compliance Program

As diesel emission-reducing technology has improved over the years, Oregon is still seeing significant pollution from older on-road diesel engines. One method to reduce these harmful emissions includes the installation of appropriate aftermarket retrofit technology. The 2019 Oregon Legislature responded to diesel emission concerns and passed House Bill 2007 to reduce diesel emissions across the state. The bill established deadlines, after which certain older model diesel engine vehicles cannot be titled or registered by the Department of Motor Vehicles or the Commerce and Compliance Division in Clackamas, Multnomah, and Washington counties unless equipped with approved retrofit technology and certified by DEQ. The two vehicle weight classifications categorized in HB 2007 include:

  • Medium-duty with gross vehicle weight rating of 14,001 – 26,000 lbs. (such as certain box trucks, flatbed or service trucks)
  • Heavy-duty with a gross vehicle weight rating of over 26,000 lbs. (such as tractor-trailer trucks).

Questions about registration renewal and HB 2007 diesel vehicle exemptions?

  • For medium-duty (14,001 - 26,000 lbs.) vehicles, contact DMV Customer Assistance at 503-945-5000
  • For heavy-duty (>26,000 lbs.) vehicles, email the Commerce and Compliance Division:

Reminder: Annual renewal requirements and application
As of 2024, the DEQ Diesel Retrofit Compliance Program has begun the next phase of requirements for regulated vehicle owners. See Annual Renewal Inspection Requirements timeline for a brief description of those requirements. As detailed in the Annual Renewal Inspection Timeline, regulated owners are required to have an opacity test and a visual inspection of the regulated vehicle prior to applying for certification renewal. Tests must be performed by a DEQ authorized installer. Please complete the Annual Renewal application along with inspection/test results and submit to DEQ using the HDD Online Application. Annual applications may be found below under “More Information."

Please contact the DEQ Diesel Retrofit Compliance Program with any questions.

More information

​In preparation of submitting the online application, there are several steps vehicle owners will need to complete. Below is a checklist and summary of the application process.

Step 1: 

After completion of the vehicle retrofit installation, Oregon DEQ requires the following documents to be ready prior to submitting the application.  The Signature of Attestation will need to be completed and signed by the registered owner or authorized representative. The installer will also need to sign the Installer Certification Section. The other documents listed below should be provided by the installer.

Step 2:

Please ensure the following requirements have been prepared by the authorized installer:

  • Manufacturer/Installer pre-assessment form
  • Documentation and pictures supporting labeling requirements of retrofit system
  • Copy of warranty agreement between installer and owner

Step 3:

Please contact the Retrofit Compliance Program for information about the Approved Retrofit Technology application by email:



The Environmental Protection Agency, and California's Air Resource Board, maintain lists of currently verified retrofit technologies for on-road diesel engines, proven to achieve at least an 85% reduction in diesel particulate matter. Currently verified EPA or CARB retrofit technologies, otherwise known as diesel particulate filter or DPF systems, may qualify as Approved Retrofit Technology for Oregon's Retrofit Compliance Program. To meet the criteria for Approved Retrofit Technology, DEQ will need to verify that the technology meets the following:

  • The new equipment is manufactured for installation on an on-road diesel engine and compatible with the medium- or heavy-duty truck;
  • Provides at least 85% reduction of diesel particulate matter and currently verified by EPA or CARB;
  • Installed by an installer authorized by the Approved Retrofit Technology manufacturer;
  • Has a valid manufacturer's warranty; and​
  • Complies with labeling and inspection requirements.

​​The Environmental Quality Commission, Oregon DEQ's formal policy and rulemaking body, adopted the Diesel Retrofit Compliance rules on July 23, 2021. The rules provide additional details and clarity to the direction provided in HB 2007 (2019) related to approved retrofit technologies and program implementation. They establish the criteria for approved retrofit technologies for on-road diesel engines, the manner by which Oregon DEQ will certify them and the verification required to ensure continued certification for those technologies. The certificate of retrofit compliance, issued by DEQ, would allow the owner to renew or title a vehicle per the Oregon Vehicle Code found in Oregon Department of Transportation Statute Chapter 803. Please visit the DEQ rulemaking page below for more information regarding the adopted rule. 

Please follow the links provided to find the diesel retrofit compliance rules:


HB 2007 (2019) authorized DEQ's Diesel Emissions Mitigation Grant Program to provide grant funding, subject to availability, to support the purchase of retrofit systems, as well as cleaner burning engines and diesel equipment replacements. Vehicle owners who apply and are awarded the grant funding, will be eligible for up to 100% of the retrofit technology cost. DEQ intends to have approximately $8 million available each year beginning in 2021 with a target of providing at least five years of funding based on available revenue. Please refer to our Diesel Emissions Mitigation Grants web page for key dates and more detailed information.


Please contact the DEQ Diesel Retrofit Compliance Program for any questions regarding this program:  

David Glomski
Operations and Policy Analyst
Portland Area: 503-229-5066
Toll-Free in Oregon: 877-476-0583