Remanufactured CP4.2 High-Pressure Fuel Injection Pump — 2011–2016 Chevy/GMC 6.6L Duramax LML & LGH

Direct replacement CP4.2 high-pressure fuel injection pump for 2011–2016 Chevrolet Silverado and GMC Sierra 2500HD/3500HD with the 6.6L Duramax LML engine, as well as LGH-equipped Express/Savana vans and medium-duty trucks. Remanufactured to OEM specifications using original equipment or OE-validated components, assembled and tested on state-of-the-art Bosch-calibrated equipment.

Why the CP4 Fails

The Bosch CP4.2 replaced the proven CP3 starting in 2011. It creates higher fuel pressure with less volume — more efficient, but far less tolerant of fuel quality issues. The CP4’s ultra-tight internal tolerances make it vulnerable to cavitation, water contamination, and the reduced lubricity of modern ultra-low sulfur diesel (ULSD). When a CP4 fails, it doesn’t just stop working — it grenades, sending metal shavings through the entire high-pressure fuel system: rails, lines, and all 8 injectors.

A CP4 failure typically costs $8,000–$12,000+ when the entire fuel system needs replacement. Catching low rail pressure early and replacing just the pump before catastrophic failure saves thousands. Read our complete guide: Duramax CP4 Failure: Symptoms, Causes & What to Do

What’s Different About This Pump

This is not a used or “rebuilt” pump with just new seals. Every unit is fully remanufactured with OEM or OE-validated components, then tested through 10+ quality checks including fuel delivery from cranking to full-load RPM, leak testing, and torque curve verification. The pump ships ready to install with no additional parts or modifications needed.

Specifications

Fitment

• 2011–2016 Chevrolet Silverado 2500HD / 3500HD (6.6L Duramax LML)
• 2011–2016 GMC Sierra 2500HD / 3500HD (6.6L Duramax LML)
• 2011–2016 Chevrolet Express / GMC Savana (6.6L Duramax LGH)
• Medium-duty GM/International trucks with 6.6L Duramax LGH

Cross-Reference Part Numbers

This pump replaces the following OEM and aftermarket part numbers:

Signs Your CP4 Is Failing

Don’t wait for catastrophic failure. If you’re seeing any of these symptoms, your CP4 may be on its way out:

• Low rail pressure codes — P0087 (fuel rail pressure too low), P0088, P228D
• Hard starting or extended crank
• Loss of power under load — especially noticeable when towing
• Engine stumbling or surging at highway speeds
• Actual vs. desired rail pressure deviation — if you’re monitoring with a scan tool or Banks iDash, watch for the gap widening
• Metal shavings in the fuel filter — if you see glitter in the filter, the pump has already started to self-destruct

⚠️ Critical: If you find metal in your fuel filter, do NOT just replace the pump. The contamination has likely spread to the injectors, rails, and fuel lines. At that point, the entire high-pressure fuel system needs replacement to prevent repeat failure. Contact us for a complete fuel system assessment.

Installation Notes

• This pump is a direct drop-in replacement — no modifications, tuning, or additional hardware required
• Always replace the fuel filter before installing a new pump
• Inspect the fuel filter housing for metal contamination before installation — if metal is present, the entire fuel system needs attention
• Consider adding a fuel additive like Stanadyne Performance Formula to improve fuel lubricity and extend CP4 life
• A quality lift pump with fine filtration (2–10 micron) can significantly reduce the risk of future CP4 failure by delivering cleaner fuel at consistent pressure

CP4 Replacement vs. CP3 Conversion

Some owners choose to convert from the factory CP4 to a CP3 injection pump for maximum reliability. A CP3 conversion eliminates the catastrophic failure risk entirely but costs $3,500–$7,000 and requires additional components, tuning, and labor. Replacing the CP4 with a quality remanufactured unit is the more affordable and straightforward option — especially if the rest of the fuel system is clean. Read our complete comparison: Duramax CP4 to CP3 Conversion: Is It Worth It?

Why Buy From Valley Fuel Injection?

We’re not an online parts catalog — we’re a Bosch-certified diesel fuel injection service center and authorized Alliant Power dealer with over 45 years of hands-on diesel injection experience. We test and rebuild injection pumps on Bosch-calibrated equipment every day. When you buy a CP4 from us, you’re buying from a shop that understands the entire fuel system — not a warehouse that ships boxes.

Need help diagnosing a CP4 issue or determining if your fuel system needs a full replacement? Call us at (530) 668-0818.