On June 10 at the Great American Fair in Washington, D.C., EPA Administrator Lee Zeldin announced a proposed rule that amends the controversial warranty and useful life elements of the low-NOx rules for MY2027 heavy-duty engines, while also putting an indefinite end to DEF derates for new vehicles. OEMs will also receive some leeway regarding the sale of engines that do not conform with the upcoming NOx standards.

If the proposal goes forward (and it would be shocking if it did not), here’s what will change from the initial low-NOx rule created during the Biden administration:

• NOx limits stay at 0.035 grams per horsepower-hour during normal operation, 0.05 grams at low load, and 10 grams at idle
• Warranty requirements return from 450,000 miles back to 100,000 miles
• Useful life requirements of 11 years/650,000 miles (or 32,000 hours) will go into effect 2030

The EPA press release called the Biden requirements “unnecessary and unworkable,” and estimated that these “commonsense” changes will save American truckers $12 billion.

“If finalized, these [NOx rule] changes will help manufacturers keep improving their vehicles without being forced to rush products to market before they’re ready,” Zeldin stated. “Combined with the Trump EPA’s first proposed deregulatory action to address ongoing DEF problems, this will ease real burdens for operators.”

OEMs will also get some flexibility from revisions that allow 5% of U.S. trucks to meet pre-2027 requirements. They can also pay a fee to sell medium-heavy and heavy-heavy duty trucks that don’t meet the 0.035 g/bhp-hr threshold, and the EPA is also looking into expanding the availability and flexibility of NOx credits.

DEF changes

Under the proposed rule, the EPA explained that “instead of trucks and tractors lurching to a halt when DEF systems fail…operators would receive visible and/or audible alerts that allow them to continue operating until they can safely address the problem.”

By eliminating derates and vehicle speed restrictions, EPA said upwards of $6,000 could be saved per new truck, along with avoiding any productivity losses incurred due to downtime. And according to Zeldin, who said he has spoken at length with farmers and truckers on the topic, “the systems that manage DEF don’t always work right.”

While an operator failing to fill the DEF tank would cause a derate, so would a defective sensor in an otherwise working SCR.

This is an evolution of the EPA’s previous strategy of advising OEMs to implement software updates that extend the grace period between DEF faults and derates. Paccar and Daimler Truck North America have already released updates this year to comply with the request.

Industry response

While Fleet Maintenance cannot confirm the veracity of the savings estimate, we have reported at length how unpopular the low-NOx final rule was and that it would greatly increase the cost of new heavy-duty trucks. Since Trump was elected, OEM sources and leaders of the American Trucking Associations (ATA) have been tentatively optimistic that the warranty and useful life aspects would come down to earth. ATA had specifically requested the rollback via a letter sent in February.

ATA President and CEO Chris Spear joined Zeldin on the National Mall dais to discuss the announcement, as did the heads of Cummins’ Jennifer Rumsey, DTNA’s John O’Leary, and Paccar CEO Preston Feight.

“It’s absolutely a breath of fresh air,” said O’Leary, commenting on the current administration’s “very different approach” of listening to the manufacturers.

He stressed that the OEMs also strive for a better environment, but “in a way that makes sense, that doesn’t bankrupt businesses.”

“Beyond listening, it’s leadership,” Spear said. “That’s such a sea change to be able to work collaboratively with the EPA under this administration has been very uplifting.”

But EPA’s 2022 rule demanded another 80% reduction in NOx emissions in just five years, forcing our industry to confront costly, complex technologies that have not been fully proven in real-world conditions.”

The Owner-Operator Independent Drivers Association, though, criticized the failure to ease the NOx limits, while lowering the warranty and useful life, which can protect independent truckers when new technology fails.

OOIDA Director of Federal Affairs, Jay Grimes, stated:

"Unfortunately, the NPRM marks a missed opportunity to adequately correct the shortcomings of the 2023 Final Rule. If EPA is unable to amend burdensome NOx emissions standards, we believe there are more productive solutions than drastically cutting extended warranty periods for small-business truckers at the behest of engine manufacturers and large fleets.

The rule should ensure that truckers who purchase a new vehicle will not be constantly sidelined because of costly and repeated breakdowns that OOIDA members have historically experienced under new emissions regulations. Given these concerns, sensible warranty programs are critical for encouraging adoption of newer trucks."

For example, Peter Zalzal, distinguished counsel and associate vice president for clean air strategies at the Environmental Defense Fund, stated:

“This Trump EPA proposal to weaken vital clean air protections will mean more health harms and higher costs in communities across the country. Heavy duty diesel vehicles like freight trucks and buses emit huge amounts of smog and soot-forming pollution into the air we breathe, but truck makers are already introducing new engines that can substantially cut this pollution and meet protective standards. EPA should abandon this proposal and instead maintain strong pollution safeguards for new heavy-duty vehicles.”

In a statement released after the event, Spear noted that: “Since 1970, trucking has reduced heavy-duty emissions by 99%. That is real progress, and no one should pretend otherwise.”

The EPA will hold a virtual public hearing on the proposed rule on July 29-30, with all written comments due August 29. For more info, visit the EPA website.