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New Diesel Engines Come With Fewer Headaches, OEMs Say
OTA Updates, Predictive Analytics to Aid Fleet Engine Techs
Key Takeaways:
- Truck and engine manufacturers at ACT Expo in Las Vegas said EPA 2027-compliant diesel engines will deliver longer service intervals and less downtime through predictive maintenance tools.
- OEMs said limited hardware changes for stricter 35 mg/hp-hr NOx standards and expanded over-the-air diagnostics could reduce maintenance costs and unplanned repairs.
- Truck makers await EPA’s proposed rule by June and said unresolved warranty requirements will determine how much 2027-compliant engines increase vehicle prices.
LAS VEGAS — Fleets can expect longer service intervals and less downtime for the latest generation of diesel engines, according to truck manufacturers.
The Environmental Protection Agency is set to leave in place a Biden-era requirement that nitrogen oxides emissions from heavy-duty trucks drop to 35 milligrams per horsepower-hour from 200 mg/hp-hr.
Part of the reason for the service expectations is that truck makers introduced little to no new technology to meet the stricter emissions standards and that fleets can now receive over-the-air updates and take advantage of software advances that allow maintenance teams to assess wear and tear proactively.
“We made sure that going into 2027, our service intervals are improving,” International Motors Director of Engineering Navtej Singh told 2026 Advanced Clean Transportation Expo attendees.
Over-the-air updates about service will allow a carrier to obtain advance notice of an upcoming problem, Singh added during a May 4 ACT Expo panel.
Lyle Kocher, Cummins technical programs and planning director and a fellow panelist, said predictive prognostics were a step forward in ensuring the complexity of engines does not add to downtime.
“I think the fleets that are out there that are able to embrace the new tools, the new portals to be able to look and manage their fleets ahead of time are going to be well placed to be able to take full advantage of the things that are going to be offered in the upcoming years,” Kocher said.
Unplanned maintenance is one of the most frustrating pain points for fleets, Kocher noted, so predictive maintenance schedules can help with total cost of ownership.
Still, engine changes accompanying the decrease in NOx emissions are nowhere near as sizable as those for bridging the gap between 2007 and 2010 compliance.
Volvo Group divisions Volvo Trucks North America and Mack Trucks both unveiled their EPA 2027-compliant engines at ACT Expo.
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Volvo's 2027 EPA compatible D13 engine on display at ACT Expo 2026. (Keiron Greenhalgh/Transport Topics)
VTNA on May 4 pulled back the curtain on a D13 engine compatible with the standards. The company will offer the engine as part of the standard package for the VNL and VNR on-highway Class 8 tractors.
A day later, on May 5, Mack unveiled an MP13 engine compliant with the regulations. It will be available for the Pioneer and Anthem on-highway tractors plus the vocational market-focused Granite and Keystone models, Mack said.
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Mack's EPA 2027-compliant MP13 engine. (Mack Trucks)
The full details on the regulations have yet to be made public, but truck manufacturer executives said at ACT Expo they expect a notice of proposed rulemaking by the end of June.
An NPRM is a formal document issued by a federal agency that announces the intent to change, add or remove regulations. It outlines the proposal and invites public comment.
Beyond leaving the Biden-era requirement in place, the trucking industry is still waiting for clarity on key details, including warranty requirements.
Retention of the current warranty length would be welcomed by fleets, as it likely would limit cost increases. Some OEMs told carriers at ACT Expo that potential price hikes could be halved if warranty terms remain unchanged.
EPA told Transport Topics in early May that it is working to re-evaluate the rule and is planning to propose a rule in the “spring of 2026.”
No manufacturers have revealed price lists yet because of the delays to the NPRM, but some were not waiting for the agency before showcasing their products.
DTNA’s Detroit unit in February launched three engines for Freightliner and Western Star trucks that comply with the NOx regulations. The Gen 6 portfolio comprises the 13-liter DD13, 15-liter DD15 and 16-liter DD16 engines.
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A Gen 6 engine. (Detroit via broadhead)
The biggest change on the engines, DTNA Director of Field Sales Engineering Steve Collins told ACT Expo attendees, is a simplification of the fuel system.
“We had a ... pretty complicated fuel system in our previous generation,” Collins said, noting that non-amplified injectors utilizing an oil-lubricated high-pressure fuel pump were added. The changes were intended to simplify maintenance, he explained.
Cummins unveiled its EPA 2027-compliant X15 diesel engine at the Technology & Maintenance Council Annual Meeting, emphasizing a redesigned, larger selective catalytic reduction system and fuel-efficiency gains. The engine is rated up to 605 horsepower and 2,050 pound-feet of torque.
Lingering uncertainty over the NOx rule’s future, stemming from EPA statements from March 2025 about stalling the pending regulations, compelled Cummins in August to delay the launch of its 2027-compliant X15 diesel engine.
International was the first of the major engine makers to detail its plans for an EPA 2027-compliant engine in January. Enhancements for the updated S13 powertrain included variable valve timing and a 24-volt transmission control module for the T14 transmission with predictive shifting using GPS and topography data.
