Cummins, Inc., the manufacturer of the X15 series of heavy-duty diesel motors, received bad news from the United States District Court for the Western District of Michigan on April 22, 2025, when the court denied Cummins’s motion to strike class allegations from the civil complaint of West Michigan trucking company SBS Transport, LLC. Westbrook Law PLLC represents SBS in the lawsuit, which alleges that Cummins routinely and unlawfully denied warranty claims when X15 motors failed, based on false assertions that the motors were “dusted,” or damaged by excessive dirt or dust ingestion that voided the warranty.

Two of SBS’s X15 motors failed within a one-year span. Cummins denied warranty coverage in both instances, claiming that “dusting” was to blame for the failure. Cummins’s claims of “dusting” have created tension between Cummins and the truck manufacturers it supplies with engines, including Kenworth and Peterbilt, as Cummins’s claims point the finger at them for the failures of its X15 engines. Meanwhile, Kenworth and Peterbilt service centers have repeatedly observed Cummins claiming that an X15 is “dusted” when diagnostics do not support that conclusion. The lawsuit claims this “diagnosis” by Cummins is merely a pretext to avoid paying for expensive repairs, which may total tens of thousands of dollars for each affected engine. The case asserts two counts: breach of warranty, asserted on behalf of SBS and a nationwide class of X15 purchasers; and violation of Michigan’s Motor Vehicle Service and Repair Act, asserted on behalf of SBS and a class of Michigan-based fleet owners.

If you are an owner of a Cummins X15 engine produced since 2016 and had warranty claims denied due to “dusting,” we would like to hear your story. Contact us.

TJW