July 2026

CP4 Fuel Pump Settlement: What Every 2011-2016 Duramax Owner Must Know in 2026

If you own or previously owned a 2011-2016 Chevrolet Silverado or GMC Sierra with a 6.6L Duramax diesel engine, you may still be eligible for cash payments or partial repair reimbursement through the CP4 fuel pump settlement – but time is running out. The $50 million class action settlement in Chapman v. General Motors LLC has already begun distributing payments, yet thousands of eligible owners still haven't claimed what they're owed. Here is everything you need to know right now.

The Bottom Line: What You Need to Know Today (July 2026)

The CP4 fuel pump settlement is real, the money has started flowing, and your window to take action is closing fast. Initial distribution payments were issued on March 23, 2026, according to the official settlement website. If you paid out of pocket for a CP4 repair before May 6, 2025, or if you sold your truck before that date without having the pump repaired, you should have already filed a claim. That deadline – November 6, 2025 – has passed. However, if you still own your truck and have not yet had a CP4 failure, the Partial Repair Reimbursement Program is still active until May 6, 2026, or until your truck hits 200,000 miles. Given today is July 10, 2026, that deadline has now passed as well. But if you had a qualifying repair performed between May 6, 2025 and May 6, 2026, you still have until July 5, 2026 to submit your reimbursement request form.

Yes, that means the deadline is only days away as of this writing.

What Is the CP4 Fuel Pump Lawsuit About?

The lawsuit alleges that General Motors knowingly sold diesel trucks equipped with a defective Bosch CP4 high-pressure fuel injection pump. Unlike the older, more reliable CP3 pump, the CP4 uses a two-plunger design that relies entirely on diesel fuel for lubrication. American diesel fuel – Ultra Low Sulfur Diesel (ULSD) – provides significantly less lubrication than European diesel, causing the pump's internal components to grind against each other. This generates metal shavings that contaminate the entire high-pressure fuel injection system, including the fuel rail and all eight injectors. The result can be catastrophic failure, often without warning, potentially causing the engine to shut off while driving.

GM denies any wrongdoing and maintains that the fuel pumps are not defective. However, rather than continuing litigation, the company agreed to a $50 million settlement to avoid the costs and risks of trial.

Who Is Eligible for the CP4 Fuel Pump Settlement?

You are a Settlement Class Member if you purchased a model year 2011–2016 Chevrolet Silverado or GMC Sierra equipped with a 6.6L Duramax diesel engine from a GM-authorized dealer in one of these seven states:

California
Florida
Illinois
Iowa
New York
Pennsylvania
Texas

Your purchase must have occurred between March 1, 2010, and September 13, 2024 to qualify. The specific engine involved is the LML variant of the 6.6L Duramax, which uses the Bosch CP4 pump.

To check if your specific truck is included, you can enter your Vehicle Identification Number (VIN) on the official settlement website's VIN lookup tool.

What Are the Settlement Benefits?

The settlement provides three main types of benefits:

1. Cash Payments for Past Repairs (Deadline Passed)

A $30 million fund was established to compensate class members who paid out of pocket for CP4 fuel pump repairs that were not covered by warranty. Depending on the number of valid claims and the cost of your repair, payments were estimated to range from $6,356 to $12,712. However, the deadline to file a claim for past repairs was November 6, 2025, and has now passed.

2. Cash Payments for Former Owners Who Never Repaired (Deadline Passed)

A separate $5 million fund was created for class members who no longer own their truck and did not pay for a CP4 repair while they owned it. Estimated payments ranged from $400 to $800. Again, the November 6, 2025 deadline has passed.

3. Partial Repair Reimbursement for Future Repairs (Urgent Action Needed)

This is the benefit that may still apply to you if you act fast. The Partial Repair Reimbursement Program covers 50% of the cost of a CP4 repair or replacement performed at a GM-authorized dealership on or after May 6, 2025. The program runs for one year from the date of final approval – meaning it ends on May 6, 2026, or when the vehicle reaches 200,000 miles, whichever comes first.

Critical for current owners: If your CP4 pump failed between May 6, 2025 and May 6, 2026, and you had the repair done at a GM dealership, you have 60 days from the date of repair to submit your reimbursement request. For repairs done near the end of the program (May 2026), that 60-day window extends into July 2026. The final deadline to file a Reimbursement Request Form is July 5, 2026.

How Much Money Could You Receive?

Here is a breakdown of estimated payment amounts based on your situation:

Owner Category	Estimated Payment	Status
Current owner who paid for CP4 repair before May 6, 2025	$6,356 – $12,712	Deadline passed (Nov 6, 2025)
Former owner who never repaired CP4	$400 – $800	Deadline passed (Nov 6, 2025)
Current owner with qualifying repair May 6, 2025 – May 6, 2026	50% of repair cost (avg. ~$5,000)	Must file by July 5, 2026

These amounts are estimates. Final payouts depend on the total number of valid claims and court-approved allocation.

What Documentation Do You Need?

If you are filing for reimbursement under the Partial Repair Reimbursement Program, you will need:

Proof of Purchase: Documentation showing you purchased your truck from a GM-authorized dealer in one of the covered states during the eligible period. This can be a purchase agreement or financing document.

Proof of Repair: A repair order or invoice from the GM-authorized dealership that performed the work. It must include your name, the VIN, and clearly identify the covered components (CP4 pump, injectors, fuel rail, etc.).

Proof of Payment: Bank statements or credit card records showing you paid out of pocket for the repair.

Timing: Your reimbursement request must be submitted within 60 days of the repair date.

What the CP4 Settlement Does NOT Cover

It is important to understand the limitations of this settlement:

CP3 conversions are not covered. Many Duramax owners have proactively replaced their CP4 pump with the older, more reliable CP3 design. These conversions typically cost $3,000 to $5,000 and solve the reliability issue. However, the court specifically mandated that reimbursements only apply to repairs performed at GM-authorized dealerships using OEM parts.

Repairs at independent shops are not covered. Even if your local diesel shop did excellent work, the settlement only reimburses repairs done at GM-authorized dealerships.

Vehicles over 200,000 miles are excluded. The Partial Repair Reimbursement Program ends when the vehicle reaches 200,000 miles, regardless of when the repair was performed.

Trucks outside the seven covered states are not included. If you purchased your truck in a state other than California, Florida, Illinois, Iowa, New York, Pennsylvania, or Texas, you are not part of this settlement class.

The Defect: Why the CP4 Pump Fails

Understanding the defect helps you appreciate why this settlement matters. The Bosch CP4 pump was designed for European diesel fuel specifications, which have different lubrication properties than the Ultra Low Sulfur Diesel used in the United States. Because American diesel provides less natural lubrication, the pump's internal components – roller bearings, cam lobes, and pistons – experience increased metal-to-metal contact.

Over time, this friction generates microscopic metal shavings that circulate through the entire high-pressure fuel system. These shavings contaminate the fuel rail, all eight injectors, and the low-pressure lines. Unlike the older CP3 pump, which typically lost power gradually, the CP4 can fail suddenly and without warning, potentially causing the engine to shut off while the vehicle is in motion.

Repair costs for a complete CP4 failure are substantial. Because the metal debris spreads throughout the system, a typical repair requires replacing the pump, all eight injectors, the fuel rail, fuel lines, and sometimes the tank and low-pressure lines. Total costs commonly range from $10,000 to $18,000, with most cases falling between $12,000 and $14,000.

Case History and Timeline

The lawsuit, Chapman v. General Motors LLC, was filed on August 6, 2019, in the U.S. District Court for the Eastern District of Michigan under case number 2:19-cv-12333. The original plaintiffs included Clay Kincheloe, William McDuffie, Bryan Joyce, Leroy Gwinn Jr., Tim Taylor, Mark D. Chapman, Gary Godwin, and Robert Hoag.

The case was assigned to U.S. District Judge Terrence G. Berg. Three law firms were appointed as Class Counsel: Hagens Berman Sobol Shapiro LLP (Seattle, WA), Hilliard Law (Corpus Christi, TX), and The Miller Law Firm, P.C. (Rochester, MI).

After years of litigation, a Final Approval Hearing was held on April 25, 2025. Judge Berg granted final approval on May 6, 2025, and the case was dismissed with prejudice.

Initial distribution payments to approved claimants were mailed on March 23, 2026. Additional distributions are scheduled for August 2026 for class members who provided documentation to cure deficient claims.

What Should You Do Right Now?

Given today's date of July 10, 2026, here is your actionable checklist:

If you had a CP4 repair performed at a GM-authorized dealership between May 6, 2025 and May 6, 2026: File your Reimbursement Request Form immediately. The final deadline is July 5, 2026, which has already passed. If you have not yet filed, you still have a few days – submit your documentation online at the official settlement website or mail it to the address provided.

If you previously submitted a claim and received a Notice of Deficient Claim: Check your mail. Notices are being reviewed, and you may need to provide additional documentation. An additional distribution will be made in August 2026 to class members who cure their deficient claims.

If you own a class truck that has not yet experienced a CP4 failure: Unfortunately, the Partial Repair Reimbursement Program expired on May 6, 2026. You are no longer eligible for the 50% reimbursement benefit. Consider proactive options such as a CP3 conversion (though not covered by this settlement) or monitoring your truck closely for early warning signs.

If you are unsure about your eligibility: Visit the official settlement website at www.gmfuelpumplitigation.com and use the VIN lookup tool. You can also call 1-866-848-0815 or email info@GMFuelPumpLitigation.com for assistance.

Important Distinction: This Is Not a Recall

It is critical to understand that the CP4 fuel pump settlement is a class action lawsuit settlement, not a government-issued recall. While GM issued a separate recall in March 2026 (NHTSA Campaign 26V129000) for certain 2025-2026 Silverado and Sierra 3500 HD trucks with gas engines and dual fuel tanks, that recall involves a completely different issue – a fuel transfer defect that can cause engine stalling. That recall does not apply to the 2011-2016 Duramax diesel trucks covered by this settlement.

Final Thoughts

The CP4 fuel pump settlement represents a significant victory for Duramax owners who experienced costly repairs due to a pump defect that should never have been installed in these trucks. While the deadlines for past-repair claims and former owner claims have passed, the Partial Repair Reimbursement Program offers a last-chance opportunity for owners who had qualifying repairs performed in the past year.

Do not wait. If you have documentation of a CP4 repair at a GM dealership between May 6, 2025 and May 6, 2026, gather your paperwork and file your claim today. The difference between receiving 50% of your repair cost and receiving nothing is measured in days.