Car Complaints reports that GM is facing yet another class action lawsuit over brake master cylinder defects in five 2025 models. Plaintiffs from Pennsylvania, New York, and Missouri allege that internal seals inside the master cylinder fail prematurely, leaking brake fluid and causing a sudden loss of hydraulic pressure. A damaged master cylinder can trigger a warning light, make the pedal feel hard, or cause the pedal to fall straight to the floor.
The initial lawsuit, filed in October 2025, only covers New York and Pennsylvania. The re-filed complaint adds Missouri and targets anyone who purchased or leased a 2025 Chevy Traverse, 2025 GMC Acadia, 2025 Buick Enclave, 2025 Chevy Colorado, or 2025 GMC Canyon in those three states.
Pennsylvania plaintiff Eric Barron owns a 2025 Chevrolet Traverse. General Motors replaced his defective master cylinder for free, but Barron complained that the loaned vehicle was smaller than his Traverse. New York plaintiff Chelsey Thompson also owns a 2025 Traverse. She claims GM violated the New York Lemon Law and express warranties. Missouri plaintiff Simon Moeller rounds out the trio; His 2025 GMC Acadia suffered the same failure.
Each plaintiff sued General Motors for breach of express warranty, breach of implied warranty of merchantability, fraudulent concealment, and unjust enrichment.
The lawsuit follows GM’s issuance of Service Update N242482170, which addresses a master cylinder issue on 2024 Chevy Traverse and 2025 Buick Enclave vehicles. “Certain vehicles listed above may have a condition where the internal cartridge seal in the eBoost Module is missing,” the bulletin states. “The dealer had to replace the brake master cylinder.”
General Motors argued none of the plaintiffs owned the vehicles named in the service updates. The lawsuit argues that the same braking system components – and the same defective master cylinder – are present in all five 2025 models. The plaintiffs also point to “a higher-than-expected number of replacement master brake cylinder assemblies ordered by GM dealers” as evidence that the automaker was aware of the defect.
The case is Barron, et al., v. General Motors LLC in the U.S. District Court for the Eastern District of Pennsylvania. Attorney Sergei Lemberg represents the plaintiff.
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