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Hagens Berman: Judge Allows Class-Action Lawsuit to Continue for Owners of Defective GMC and Chevy Diesel Trucks

Court greenlights claims on behalf of classes of consumers suffering from defective Bosch CP4 fuel pumps installed in Duramax diesels

A federal judge has certified seven classes of consumers in a lawsuit against General Motors accusing the automaker of knowingly selling diesel trucks equipped with defective Bosch CP4 fuel pumps, according to attorneys at Hagens Berman and Hilliard Martinez Gonzalez LLP.

The class-action lawsuit was originally filed Dec. 2, 2019, and states that due to the defective Bosch part, the following affected trucks with Duramax LGH Engines could experience catastrophic failure and lead owners to costly repair bills: 2010-2011 Chevrolet Express, 2010-2011 GMC Savana, 2010-2011 GMC Sierra, 2011-2012 2500HD 3500 Silverado and 2011-2012 2500HD 3500 Sierra. If you own an affected GMC or Chevy vehicle from a GM-authorized dealership, find out your rights.

According to experts, the affected vehicles’ CP4 pump design is fragile and fundamentally flawed in several respects, and incompatible with diesel fuel sold in America. Due to the lack of proper lubrication in U.S. diesel, the fuel causes metal shavings to build up in the fuel system and engine, leading to unexpected total engine failure.

Repair costs range from $8,000-$20,000 and, since the “repair” consists of installing an identical replacement CP4 pump, still leaves owners with defective vehicles. Owners are therefore subject to the inconvenience of an unreliable vehicle, repair costs, and the potential safety hazard of unexpected engine failure. In addition to the costs of repair, owners are left with defective vehicles for which they overpaid or would not have purchased had they known about the defect.

In Judge Terrence G. Berg’s 53-page order, consumers’ claims were upheld under various state laws, and seven classes were certified for the states of California, Florida, Illinois, Iowa, New York, Pennsylvania and Texas, in an overwhelming victory against GM. The March 31, 2023 order also appointed class counsel, acknowledging the qualifications of Hagens Berman Sobol Shapiro LLP, Hilliard Martinez Gonzalez LLP and The Miller Law Firm P.C.

The court also upheld the claims of those owners who have not experienced the defect, but have still been harmed through purchasing the defective vehicle: “…even those who have not yet experienced a failure have adequately alleged they have been damaged by overpaying for their vehicles as a consequence of GM’s failure to disclose the problems with the CP4 pump.”

“We are pleased with the court’s thoughtful analysis of the issues and look forward to continuing the case into discovery to fully uncover the exact extent of what GM knew when it chose to sell these defective diesel trucks,” said Steve Berman, managing partner at Hagens Berman. “We believe GM has greatly endangered the lives of many.”

“Judge Berg left no rock unturned, and his thoroughness speaks to the ironclad strength of our claims,” said Bob Hilliard of Hilliard Martinez Gonzalez LLP. “GM knew what was at risk when it decided to market and sell this extensive line of trucks to the public, and now GM should be held accountable for its conduct."

In outlining the claims addressed in the case, the order reads, “Plaintiffs intend to offer common proof—through testimony of GM engineers, internal testing data, and GM’s correspondence with Bosch—that GM knew of the alleged design defect even before it began production of class vehicles. They also intend to offer common proof—through testimony by GM employees, GM’s internal warranty data, GM’s instructions to dealerships, and marketing literature—that GM failed to disclose the design defect and actively concealed it even though class vehicles immediately began failing in the field.”

Find out more about the class-action lawsuit against GM for defective Bosch CP4 pumps installed in its Duramax diesel trucks.

About Hagens Berman

Hagens Berman is a global plaintiffs’ rights complex litigation law firm with a tenacious drive for achieving real results for those harmed by corporate negligence and fraud. Since its founding in 1993, the firm’s determination has earned it numerous national accolades, awards and titles of “Most Feared Plaintiff’s Firm,” MVPs and Trailblazers of class-action law. More about the law firm and its successes can be found at Follow the firm for updates and news at @ClassActionLaw.

About Hilliard Martinez Gonzales

Bob Hilliard has led HMG to the forefront of national trial law firms. Having tried over 100 jury trials, Mr. Hilliard is also a two-time winner of the National Law Journal’s prestigious Elite Trial Lawyer of the Year award, as well as being recognized as a Super Lawyer for the past 18 years. Mr. Hilliard is double board certified and recognized as one of the top 100 trial lawyers in the United States. In the past six months, HMG’s 40-lawyer firm has already secured over 100 million dollars in verdicts and settlements. For more information, visit


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