Mercedes-Benz Facing Class Action Over Alleged Piston-Failure Defect Plaguing M274 Engine

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Mercedes-Benz USA faces a proposed class action that alleges the automaker has failed to disclose to drivers that the pistons in its M274 engine are prone to premature failure, which often requires total engine replacement. 

According to the 21-page lawsuit, Mercedes-Benz has received “countless” reports and complaints from vehicle owners and lessees who’ve experienced the alleged M274 piston defect. At each turn, the case claims, Mercedes-Benz has “turned a deaf ear,” failing to make or cover repairs but also failing to provide any information whatsoever on the problem apparently plaguing its vehicles. 

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The effects of the piston defect hampering the M274 engine are so significant and pose such a safety risk that the National Highway Traffic Safety Administration began looking into the problem less than two months ago, the complaint states. 

The plaintiff, a Glendale, California resident, claims in the suit that her 2016 Mercedes-Benz C300 had roughly 95,000 miles on it when its engine began to shudder and lost power on the freeway, such that the car would no longer restart. The plaintiff was eventually informed that her M274 engine had suffered a complete piston failure in one cylinder and that pieces from the failed piston had penetrated other cylinders, the suit states. Per the suit, the plaintiff’s Mercedes-Benz dealer advised her that total engine replacement would cost approximately $20,000 or more, and neither the automaker nor the dealership offered to cover any part of the repairs, the case claims.

According to the filing, piston failure “simply does not occur in modern day vehicles absent a defect.” Neither Mercedes nor the plaintiff’s dealer made mention of the fact that piston failure was something known to happen to M274 engines due to a defect, the lawsuit alleges. 

The plaintiff ultimately spent nearly $7,000 out-of-pocket at an independent mechanic to replace the M274 engine in her five-year-old Mercedes C300 with a used long block engine, the case relays.

The lawsuit explains that pistons are integral and critical engine components in that their movement inside an engine’s cylinders compresses the combustible fuel and air mixture that ultimately propels the vehicle. A defective piston, therefore, hampers a vehicle’s ability to move under its own power, the suit stresses. Worse, a cracked piston can cause particles to disburse into other cylinders, affecting the entire engine, the case relays. 

“Here, the M274 engine left the factory assembly line with defective piston components that made failure of the car virtually certain to occur during the cars’ useful life,” the lawsuit alleges. 

According to the complaint, Mercedes-Benz knew of the defect plaguing the M274 engine prior to its sale yet disclosed nothing to consumers. 

The lawsuit looks to cover all individuals in California who are owners or lessees of a Mercedes-Benz vehicle equipped with an M274 engine. 

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