By Muzammil Abbasi 
For years, owners of certain heavy-duty GM trucks have shared stories of catastrophic and expensive breakdowns tied to a single component: the CP4 high-pressure fuel pump. What many initially wrote off as bad luck or isolated incidents was, in fact, a widespread design flaw that led to a major legal battle. If you own a 2011-2016 Chevrolet Silverado or GMC Sierra with a 6.6L Duramax diesel engine, you may be part of a historic $50 million class action settlement. This guide breaks down everything you need to know about the CP4 fuel pump defect, the resulting lawsuit, and what you can do about it.
Understanding the CP4 Fuel Pump Defect: Why It Fails
At the heart of this issue is the Bosch-supplied CP4 fuel pump, a critical component in the engine of these diesel trucks. The class action lawsuit alleged this pump was a “ticking time bomb“. The core problem is a fundamental incompatibility: the CP4 pump was designed for European diesel fuel specifications, which have higher lubricity than fuel sold in the United States.
When operated with less-lubricative U.S. diesel, the internal components of the pump are prone to premature wear. This metal-on-metal contact generates fine metal shavings that are then pumped throughout the entire high-pressure fuel system. This contamination can destroy fuel injectors, lines, and rails, leading to a sudden and complete loss of engine power—a dangerous situation if it happens at highway speeds. The resulting repair often involves replacing the entire fuel system, with costs reportedly reaching $15,000 or more.
The Lawsuit and Settlement: What GM Has Agreed To
The lawsuit, formally known as Chapman, et al. v. General Motors LLC, accused GM of knowingly selling trucks with a defective pump and failing to cover repairs under warranty. While GM has denied any wrongdoing, the company agreed to a settlement to resolve the litigation.
On May 6, 2025, a U.S. District Court granted final approval to this settlement, which is valued at $50 million. The settlement establishes several funds to compensate current and former owners, providing a clear path to financial recovery for those affected by the CP4 pump failures.
Who Qualifies for the Settlement?
You are likely a member of the settlement class if you meet the following criteria:
-
Vehicle: You purchased or leased a 2011–2016 Chevrolet Silverado or GMC Sierra 2500/3500 equipped with a 6.6L Duramax diesel engine and the Bosch CP4 pump.
-
Purchase Details: The vehicle was bought from a GM-authorized dealer.
-
Location: The purchase occurred in one of these seven states: California, Florida, Illinois, Iowa, New York, Pennsylvania, or Texas.
-
Timing: The purchase was made between March 1, 2010, and September 13, 2024.
The easiest way to confirm your truck’s eligibility is to use the VIN Lookup Tool on the official settlement website.
What the Settlement Offers: A Breakdown of Compensation
The settlement provides different types of payments depending on your situation. It’s important to note that key deadlines for past repairs have passed, but an important future benefit is still active.
Table: GM CP4 Fuel Pump Settlement Compensation Overview
| Compensation Type | Eligible Group | Potential Payment Range | Key Details & Status |
|---|---|---|---|
| Reimbursement for Past Repairs | Owners who paid out-of-pocket for a CP4 pump repair. | $6,356 to $12,712 per repair. | Deadline has passed (was Nov 6, 2025). Payout depends on total number of valid claims. |
| Payment for Former Owners | Those who sold their truck before May 6, 2025, and did not pay for a repair. | $400 to $800. | Deadline has passed (was Nov 6, 2025). Payout depends on claim volume. |
| Partial Reimbursement for Future Repairs | Current owners who need a CP4 repair on or after May 6, 2025. | 50% of repair costs (approx. up to $5,000). | ACTIVE BENEFIT. Repair must be done at a GM dealership. Program ends May 6, 2026, or when the truck reaches 200,000 miles. |
The Future Repair Reimbursement Program
For owners whose CP4 pump has not yet failed, this is the most relevant part of the settlement. It acts as a limited warranty extension. If your qualified truck’s CP4 pump fails and requires repair or replacement on or after May 6, 2025, you can get 50% of the costs reimbursed provided the work is done at a GM-authorized dealership. You must submit a reimbursement request form within 60 days of the repair date.
Important Considerations and Your Legal Rights
-
Missed Deadlines: The deadlines to file a claim for past repairs or as a former owner (November 6, 2025) and to object to or exclude yourself from the settlement (December 12, 2024) have all passed. If you missed these deadlines, you are bound by the settlement terms and cannot pursue separate legal action for the same claims against GM.
-
Owners in Other States: The settlement only covers purchases in the seven listed states. If you purchased your truck in a different state, you are not part of this class action. However, you may still have legal rights, and some law firms are investigating individual claims for owners in non-settlement states.
-
The Ford Connection: It’s worth noting that Ford Motor Company used a similar CP4 pump in its 2011-Present 6.7L Power Stroke diesel trucks and is facing ongoing, separate litigation over the same alleged defect.
Final Thoughts and Your Next Steps
The CP4 fuel pump lawsuit settlement represents a significant, though belated, acknowledgment of a serious problem that affected many loyal GM truck owners. While the opportunity to claim money for past repairs is now closed, the future repair reimbursement program remains a valuable safety net for current owners for a limited time.
If you own an eligible Silverado or Sierra, your most important step is to be prepared. Save the official settlement website information, know that you have partial coverage for a CP4 failure until May 2026, and ensure any related repair is performed at a GM dealership to qualify for the 50% reimbursement.