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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 retrofit technology. The technologies are aftermarket systems installed on a vehicle and designed to reduce diesel pollution. The 2019 Oregon Legislature responded to these concerns and passed HB 2007 (2019) to reduce diesel emissions across the state. Among other directives, HB 2007 (2019) requires DEQ to establish allowable retrofit technologies for diesel engines that power certain on-road vehicles and the manner for issuing a certificate of compliance. The bill also establishes deadlines, codified in ODOT statute, after which certain older model diesel engine vehicles cannot be titled or registered in Clackamas, Multnomah and Washington Counties. The two vehicle weight classifications categorized in HB 2007 (2019) include medium-duty with gross vehicle weight rating of 14,001 – 26,000 lbs. (such as certain box trucks, flatbed or service trucks) and heavy-duty with a gross vehicle weight rating of over 26,000 lbs. (such as tractor-trailer trucks).


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.

The Approved Retrofit Technology Application will be available mid-2022. Please contact the Retrofit Compliance Program with any questions by phone or email:
Phone numbers:
Portland Area: 503-229-5066

Toll-Free in Oregon: 877-476-0583​


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

Reznic Rick, Operations and Policy Analyst

Portland Area: 503-229-5066
Toll-Free in Oregon: 877-476-0583

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