Connecting rods are snapping in GM’s three-cylinder, one Trax at 11,581 miles

A 2024 Chevrolet Trax owned by Samantha Cook of California stopped running at approximately 11,581 miles, and a dealership found a broken connecting rod inside its 1.2-liter turbocharged three-cylinder engine. Cook and Donna Cook turned that failure into a proposed class action, filed in federal court in Delaware on March 4, 2026, alleging that the same engine can throw rods in other GM crossovers too.

Seven months on, the case has not been decided, and the engine has no recall. What exists is a detailed complaint, a company that denies liability and a set of owner reports that the lawsuit’s claims will have to be tested against.

A snapped rod, as the complaint describes it

The complaint in Cook v. General Motors LLC describes “sudden and catastrophic engine failure during normal driving, often involving connecting rod ejection through the engine block.” Owners, it says, report “a loud mechanical bang or knocking sound” before losing propulsion and steering assist. In severe cases the filing alleges a fractured rod can pierce the block, leak oil and coolant, and start a fire.

Those are allegations, not findings. No court has decided that any rod in any Trax broke because of a design or manufacturing defect, and GM has not conceded the point. The claims are worth reading closely because they describe a specific mechanism: bearing damage, oil starvation and rod failure in an engine that GM fits to four crossover models. The Weekly Driver, an enthusiast site, offers one possible route to that kind of damage that the complaint does not itself adopt: the engine uses a timing belt that runs submerged in oil, and as such belts age, degrading material can restrict the oil passages that feed the bearings. That is one outlet’s explanation of a design feature, offered without testing, and neither GM nor a court has endorsed it.

Cook’s Trax and the four models in the class

According to CarComplaints, Samantha Cook’s Trax showed a reduced-engine-power message, then stalled. The dealership diagnosed a broken connecting rod and said the engine needed replacing, but the replacement was backordered. MotorBiscuit places the failure on January 25 while she was driving.

The proposed nationwide class covers U.S. buyers and lessees of 2024-and-later Buick Encore, Buick Envista, Chevrolet Trailblazer and Chevrolet Trax vehicles with the 1.2-liter engine, which carries the RPO codes LIH and LBP. A California subclass and an implied-warranty subclass sit inside it. The counts are state-law claims under California’s Consumers Legal Remedies Act, its unfair competition statute, the Song-Beverly Act and express warranty. The plaintiffs are represented by Berger Montague PC, Milberg and Drake Law Firm, per CarComplaints, and the case is listed in Delaware as 1:26-cv-00229 on a docket-tracking service.

Concealment, the “do not replace the engine” bulletin and the warranty

The heart of the case is what GM allegedly knew and told dealers. The complaint quotes technical bulletins that, it says, document “connecting rod or crankshaft main bearing damage that would require an engine assembly replacement along with oil cooler, oil cooler lines, oil tank and turbocharger,” yet also instruct technicians “Do not replace the engine.” Plaintiffs allege GM told dealers to characterize symptoms as normal and that the company has known its engines were prone to premature internal failure since at least 2022, according to GM Authority’s summary.

Warranty coverage is the second front. GM’s powertrain coverage runs five years or 60,000 miles, but the complaint says “numerous Class Vehicle owners have experienced catastrophic engine failure both within and outside the applicable warranty periods.” A separate allegation is that replacement engines were in short supply, which left vehicles undriveable for extended stretches while owners waited; Cook’s own dealer told her the replacement unit was backordered, and the Weekly Driver reports owners waiting more than 60 days for engines.

The Weekly Driver reported in July that GM denies liability and has moved to dismiss, with no ruling yet. The same report counted 210 NHTSA complaints for 2024 and 2025 Trax models, 53 of them engine-related, and nine fire reports, three involving parked, switched-off vehicles. It found no engine recall; the only listed recall, 23V744000, concerns instrument panel software. Those figures are one outlet’s tally of a federal database, not a finding by the agency.

A lawsuit against a wider GM engine problem

The Cook case arrived after litigation over GM’s 6.2-liter L87 V8. Carscoops framed it as putting both ends of GM’s engine lineup under legal scrutiny. The L87 story has a recall behind it; the 1.2-liter has, so far, only the complaint.

The next real marker is whether the 1.2-liter suit survives a motion to dismiss. Until a judge rules, or NHTSA opens an investigation, the strongest evidence in public is the 11,581-mile Trax and the bulletins the plaintiffs say GM wrote.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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