The 1.2-liter turbocharged three-cylinder at the heart of the Chevrolet Trax and Buick Encore has been hit with a lawsuit and claims that known, and possibly terminal, defects in the engine have been covered up by both General Motors and its dealership network since 2022. GM’s 1.2-Liter Turbo Engine Problem General MotorsThe lawsuit concerns the 2024 model year and younger Trax and Encore SUVs, as well as the similarly engined Buick Envista and Chevrolet Trailblazer, four of only seven vehicles with a three-cylinder engine that are currently on sale. The class action suit was filed by California plaintiffs Samantha Cook and Donna Cook after an incident that occurred on January 25.Samantha Cook, at the wheel of her newly-bought 2024 Trax, received a reduced engine power message shortly before a loud knocking noise was heard from the engine bay. Coasting to a halt, the three-cylinder engine then stalled and, once parked up, could not be restarted. The cause was later found to be a connecting rod that had pierced the engine block.At the time of the incident, the engine had only 11,581 miles on the clock. However, despite Chevrolet’s warranty program for the Trax covering five years, or up to 60,000 miles, and with the program expressly covering the engine, transmission, the drive system, and the transaxle, Ms. Cook is said to have suffered "substantial out-of-pocket expenses for engine replacement and related damage." The exact nature of these expenses has not been publicly revealed. Lawsuit Claims Defect Was Known As Early As 2022 General MotorsAccording to Ms. Cook’s dealership, the damage caused by the connecting rod failure – which can cause fluid leaks from the unit, and, alongside a loss of power, is a significant fire risk – is terminal, and a replacement engine is required. The replacement 1.2-liter turbo three-cylinder, however, is currently only on back order, and, with no arrival date confirmed, the 2024 Trax will be out of action for some considerable time.With so many engines apparently on back order, and with similar issues having been reported so early into the engine’s lifecycle, the lawsuit claims that both GM and its dealerships knew about potential defects, and, allegedly, have tried to cover them up. The lawsuit further claims these issues were potentially known during development of the second-generation Trax, which was launched in 2023. During the early Discovery phase of the trial, the plaintiff states:"Discovery will show that, since 2022, if not earlier, Defendant has been aware the Class Vehicles’ engines were prone to premature internal failure, including bearing and connecting-rod damage, oil leakage, loss of propulsion, and fire."-Representative for plaintiff Samantha Cook, via Car ComplaintsCarBuzz has reached out to General Motors for comment on this subject. News of this three-cylinder engine lawsuit also comes less than six months after additional legal action against another General Motors-built engine, the 6.2-liter L87 V8, was resolved.