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Class-Action status granted for lawsuit over defective GM CP4 fuel pumps


A federal judge has granted class-action status in a lawsuit over defective GM CP4 fuel pumps. It accuses the automaker of knowingly selling diesel trucks equipped with this pump.

The ruling comes as a significant victory for consumers, who claim that due to the defective Bosch CP4 fuel pumps, affected trucks with Duramax LGH Engines could experience catastrophic failure and lead owners to costly repair bills.

Fragile Design and Incompatibility with U.S. Diesel Fuel

Experts claim that 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.

High Repair Costs and Inconvenience over GM CP4 fuel pumps

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.

Claims Upheld for Those Who Have Not Yet Experienced Defect

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. The order reads, “…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.”

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.”

Affected vehicles include:

  • Chevrolet Silverado 2500HD 6.6L V8 Duramax Diesel with LML Engines, 2011–2016
  • Chevrolet Silverado 2500HD 3500 6.6L V8 Duramax Diesel with LGH Engines, 2011–2012
  • Chevrolet Silverado 3500HD 6.6L V8 Duramax Diesel with LML Engines, 2011–2016
  • GMC Sierra 2500HD 6.6L V8 Duramax Diesel with LML Engines, 2011–2016
  • GMC Sierra 2500HD 3500 6.6L V8 Duramax Diesel with LGH Engines, 2011–2012
  • GMC Sierra 3500HD 6.6L V8 Duramax Diesel Trucks with LML Engines, 2011–2016
  • GMC Sierra with RPO ZW9 with Duramax LGH Engines, 2010–2011

Owners can find out more about this lawsuit here.

The bottom line

We have been following these class-action lawsuits closely about the notorious CP4 fuel pump and have heard many complaints from our audience. If you are affected, you understand the frustration and if you haven’t been affected, it truly seems like simply a matter of time until you will.

Tim Esterdahl

Automotive Journalist Tim Esterdahl has been a lover of trucks and SUVs for years. He has covered the industry since 2011 and has pieces in many national magazines and newspapers. In his spare time, he is often found tinkering on his '62 C10 pickup, playing golf, going hunting and hanging out with his wife and kids in Nebraska.

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  1. Anthony Rogers May 12, 2023

    I have a 4500 2021 Silverado. It cost us $98,000 dollars. We have lost over $250.000 since we’ve had it. The entire Fuel System went out and it stayed in Baton Rouge La for 5-1/2 months at the Chevrolet dealership. This wasn’t the 1st time, it haas a fuel system issue a month after we purchased the vehicle. Fast forward, can anyone quest a month later since, we took possession of the truck where it is? Don’t worry…..in Atlanta (BROKE-DOWN) again. Yes, the Fuel System again. Can someone please Help me. I’m losing everything because, GMC knew about this and has left my family & me near HOMELESS!!!!!!

  2. Michael Erk May 16, 2023

    I have a 2015 Duramax with the cp4 fuel pump. It has not failed yet. Can I still file a claim and if so who do I contact.

    1. Tim Esterdahl May 17, 2023

      The link is in the article and also here: https://www.hbsslaw.com/cases/ford-cp4-injection-pump-defect

    2. Tammie July 24, 2023

      We are in same situation . Cp4 fuel pump came apart . We need help . This has left us struggling to survive

  3. Robyn Kirk May 19, 2023

    What if you don’t live in one of the 7 states for the approved class action? Just paid $13k to get our 2015 Silverado 2500 out of the shop – in Colorado???

    1. William September 8, 2023

      Same problem with cp4. Metal shavings throughout system, one $12000.00 for repairs. Only 35,000 miles and not covered under warranty.

    2. Joseph Burton September 14, 2023


      1. Joseph Burton September 14, 2023

        I have a 2016 gmc 2500hd Denali that the cp4 pump exploded into my fuel system gm refused to warranty . Cost me over 10k to fix along with tow and lost of use for 6 weeks, I bought the truck new and still have it. They had to put another cp4 pump back in after gm said it was safe now. Found out they lied again to me .scared to use truck as designed to because pump can leave me stranded on interstate again I’m in Indiana , am I covered under the class action suit , I know from reading the courts decision I fit into the category he described.

  4. Bill May 21, 2023

    I have a 2019 GMC Sierra 3500 Diesel, and we have experienced exactly the same catastrophic fuel pump failure that is described in other articles concerning the CP4 fuel pump. It disintegrated and dispersed metal shavings throughout the fuel system. When I took the truck into a dealership for service, they told me that I needed to replace the fuel pump, and the fuel rail – but they claimed there was rust in the system and I had water in the fuel. This was plausible, since I use an auxiliary tank to fuel heavy equipment and when the truck runs low, I have occasionally filled it with fuel from that tank. So I bought their theory, and paid the 3k for them to replace the fuel rail and the fuel pump.

    Then I drove almost 600 miles to visit with my grandkids in Virginia. However, before I got to their house, I began getting error codes and knocking sounds coming from the engine. I took it to another dealership and they diagnosed the engine. They told me that the entire fuel system need to be replaced. There were metal shavings throughout the entire system.

    This sounds remarkably similar to the issues experienced by owners of earlier year model duramax engines… so I am wondering if this year model duramax is still having the same issues. (I thought GM began using a different fuel pump after 2016 year model.)

    The dealership told me it would cost me 22k to repair. Of course I can’t afford that, so I am looking into suing the first dealership, or at least have them repair it at their cost.

  5. Chevygirl July 31, 2023

    I have a 2015 GMC 3500 Duramax. My cp4 failed at 70,000 miles. They would not warranty it, and it cost us over $13,000 at the dealer, and a month without my truck. It is BS that they said they’d warranty it, then after 2 weeks, when they had the parts, they said they wouldn’t.

  6. Steve Nakamura August 26, 2023

    I purchased my 2015 Sierra 3500 HD new. After learning of the injection pump problems I traded it in on a 2023 Sierra 2500 HD. Will I be included in the class action lawsuit?

  7. Robyn Kirk September 8, 2023

    Are any comments going to be replied to by anyone???


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