Lucas Roberto

Paccar is updating the software on its MX-11 and MX-13 engines to align with revised EPA guidance intended to reduce unnecessary downtime caused by diesel exhaust fluid (DEF) inducements. The updated calibration will be installed at the factory on new Kenworth and Peterbilt trucks built after July 20, 2026. The software will also be available through Kenworth and Peterbilt dealerships for trucks built after 2018 equipped with Paccar MX-11 or MX-13 engines.

BRISTOL, Tennessee—Set against a pristine Appalachian mountain backdrop with clear skies and sweltering summer heat, dozens of truckers gathered at Bristol Motor Speedway for the 44th Annual Shell Rotella SuperRigs truck beauty contest. Temperatures climbed into the upper 80s during the June 25-27 event, with drivers sweating through the afternoons as they prepared their rigs for judging. And when the awards were handed out, one familiar truck once again rose, er, scraped, to the top.

Less than a week after Trump issued a memorandum requesting EPA Administrator Lee Zeldin to clarify vehicle owners’ repair rights and explore alternatives for certifying emissions-compliant aftermarket parts, the agency has delivered. The new EPA guidance reaffirmed that manufacturers must provide independent repair shops and vehicle owners with the same emissions-related service information, tools, and training materials they make available to their dealers.