The Pennsylvania Motor Truck Association (PMTA) is providing an important update on the status of California Air Resources Board (CARB) emissions regulations for heavy-duty trucks (Low NOx Omnibus Rule) in Pennsylvania.

On May 10, 2025, the Pennsylvania Department of Environmental Protection (DEP) announced it is extending its suspension of enforcement of the Pennsylvania Heavy-Duty Diesel Emissions Control Program until January 2, 2028. This applies to diesel-powered vehicles over 14,000 lbs and their engines, covering model years 2022 through 2027. During this period, trucks that comply with federal emissions standards—but lack CARB certification—can continue to be sold, leased, delivered, or registered in Pennsylvania.

This decision marks a major development in PMTA’s ongoing advocacy on behalf of Pennsylvania’s trucking industry.

Nearly 20 years ago, DEP adopted California’s emissions rules by reference—meaning that when CARB changes its regulations, Pennsylvania's standards automatically change too, without review, comment, or consideration by Pennsylvania residents and businesses. Beginning with MY2024, CARB imposed drastically more stringent emission and warranty standards, with even more strict standards in effect in 2027. The 2027 rule is expected to significantly raise the cost of new trucks, with estimates ranging from $25,000 to $80,000 more per truck.

PMTA raised these concerns directly with DEP, lawmakers, and in court. Thanks to that advocacy, the agency has again chosen to delay enforcement—a decision supported by the growing legal and political uncertainty surrounding CARB’s rules.

In its notice in the Pennsylvania Bulletin (see below), DEP cited two main reasons for extending the suspension:

• Pending litigation in federal court challenging the CARB standards and warranty rules.
• Congressional disapproval of the CARB-related EPA rulemaking under the Congressional Review Act, with the U.S. House voting to block the regulations as of April 30, 2025.

Notably missing from the notice was the challenge in the state’s Commonwealth Court by PMTA and three of its members, which is ongoing. This lawsuit, filed with the help of the Pacific Legal Foundation, argues that DEP cannot delegate its regulatory authority to another state.

Details on the case: https://pacificlegal.org/case/pa-trucking-diesel-carb-standards

Though PMTA is pleased that DEP recognizes that uncertainty surrounding the rule justifies a delay in enforcement for the third time, it’s important to note that DEP's non-enforcement policy does not shield sellers or fleets from potential third-party lawsuits. PMTA continues to push for stronger, permanent protections.

PMTA remains committed to defending the Pennsylvania trucking industry from costly, unvetted regulations that threaten jobs, affordability, and fairness.

For questions or to get involved in PMTA’s advocacy, contact us directly.

NOTICES

DEPARTMENT OF
ENVIRONMENTAL PROTECTION

Suspension of Enforcement of the Pennsylvania Heavy-Duty Diesel Emissions Control Program

[55 Pa.B. 3323]
[Saturday, May 10, 2025]

 The Department of Environmental Protection (Department) announces that the Department will suspend enforcement of 25 Pa. Code Chapter 126, Subchapter E (relating to Pennsylvania Heavy-Duty Diesel Emissions Control Program) until January 2, 2028. The Pennsylvania Heavy-Duty Diesel Emissions Control Program (Program) applies to the manufacturers of new diesel-powered vehicles with a gross vehicle weight rating (GVWR) of greater than 14,000 pounds or new heavy-duty diesel (HDD) engines that are used in vehicles with a GVWR of greater than 14,000 pounds that are sold, leased, offered for sale or lease, imported, delivered, purchased, rented, acquired or received in this Commonwealth. The Program requires that subject vehicles and engines be issued a California Air Resources Board (CARB) Executive Order certifying compliance with CARB emission standards. This suspension of enforcement will allow vehicles and engines subject to the Program that have not been issued a CARB Executive Order and which meet the Federal HDD emission standards to be sold, leased, offered for sale or lease, imported, delivered, purchased, rented, acquired or received in this Commonwealth during the suspension beginning with Model Year (MY) 2022 and ending with MY 2028. This suspension of enforcement supersedes the suspension notice published at 53 Pa.B. 3166 (June 10, 2023).

 In 2002, the Department's Program implemented the then current CARB emission standards for all HDD engines and vehicles that have a GVWR of 14,000 pounds in response to an emissions cheating scandal in the late 1990s, when engine manufacturers installed emission control system defeat devices. See 32 Pa.B. 2327 (May 11, 2002). The Program became effective May 11, 2002, and provided the necessary 2-year lead time to manufacturers as required under section 177(2) of the Clean Air Act (42 U.S.C. § 7507(2)). The Program's emission standards first applied to MY 2005 HDD vehicles and engines.

 The Department has decided to continue to suspend enforcement for the following reasons. First, there is pending litigation challenging certain issues surrounding those standards and associated warranty provisions in American Free Enterprise Chamber of Commerce v. U.S. Environmental Protection Agency, (9th Cir. No. 25-89), which is currently in abeyance for 120 days or until June 12, 2025, given the changes associated with the transition of the new Federal administration. Second, the United States Environmental Protection Agency sent the standards and warranty provisions to Congress for review under the Congressional Review Act (5 U.S.C. §§ 801—808). Those standards and warranty provisions were disapproved by the United States House of Representatives on April 30, 2025, (Roll Call 111, Bill No.: H. J. Res. 87 and Roll Call No.: 112, Bill No.: H. J. Res. 89). The standards and warranty provisions will be considered by the United States Senate (Senate). If disapproved by the Senate, the resolution of disapproval will be presented to the President for signature. If signed, the resolution will prevent the standards and warranty provisions from going into effect. Based on the two events, the Department decided not to begin enforcing the standards and provisions until January 2, 2028, at the earliest.

 The Department will reevaluate this suspension of enforcement no later than July 31, 2027. Manufacturers will be required to meet the Program's requirements beginning with MY 2029 HDD vehicles and engines.

 The Department's exercise of enforcement discretion does not protect a manufacturer, distributor, seller, renter, importer, leaser or owner of a retail outlet from the possibility of legal challenge by third persons under 25 Pa. Code Chapter 126, Subchapter E.

 For more information or questions concerning the requirements of the Program, contact Nicholas Lazor, Director for the Bureau of Air Quality, at nlazor@pa.gov or (717) 787-9702.

[Pa.B. Doc. No. 25-620. Filed for public inspection May 9, 2025, 9:00 a.m.]

Link to Bulletin: https://www.pacodeandbulletin.gov/Display/pabull?file=/secure/pabulletin/data/vol55/55-19/620.html