2011-2016 Chevy/GMC 6.6L Duramax LML Remanufactured CP4 Injection Pump — Bosch 0986437421
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
| Type | Bosch CP4.2 high-pressure common rail injection pump |
| Condition | Remanufactured to OEM specifications |
| Fitment | 2011–2016 GM 6.6L Duramax LML (pickup) & LGH (van/medium-duty) |
| OEM Part Number | 12638262 |
| Alliant Power Part Number | FIE20281 |
| Warranty | 24-month, unlimited mileage |
| Core Required | Yes — core charge applies, refunded on return of rebuildable core |
| Country of Origin | USA |
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:
| Bosch | 0 445 010 616, 0 445 010 687, 0 445 010 802, 0 445 010 817, 0 986 437 421 |
| GM/OEM | 12638262, 12639151, 12645102, 12645103, 12658095, 12661059, 98077841 |
| Other | IP36, IP52, DA225105, 7EX836104, 739-109, 30-3004, 19432134 |
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.
Why do I see this common rail injector cheaper online?
Short answer: it is usually not the same part — and common rail does not forgive “close enough.” Read why ↓
Search any OE number and eBay, Amazon and a dozen storefronts will show it well under dealer cost, sold by outfits with no name, no address and no phone number. We lose business to those listings every week — and we see a lot of them come back through our shop. Here is what is actually different.
- The part number proves nothing on its own. Counterfeit injectors and pumps are stamped with the same OE numbers as the real thing, in housings cast to look identical. The number in the listing title tells you what the seller claims it is, not what came off an OE line.
- “Remanufactured” is not a regulated word. A genuine reman unit is stripped to bare components, has its wear parts replaced — nozzle, plunger and barrel, solenoid, seals — and is then run on a calibration bench until it meets the original flow and response spec. A cheap one is very often cleaned, resealed, painted and shipped. Both get called remanufactured.
- No full teardown, so no idea what is worn. A proper rebuild means the unit comes apart completely and every part gets inspected and measured against spec — not just the ones that are obviously bad. Skip the teardown and you are reusing worn internals inside a freshly painted housing. It will run on the truck. It will not last.
- No factory-spec bench load testing. A unit is not finished until it has been run under load on a test bench and made its numbers across the range, not just at one easy point. That bench time is most of what you are paying for. Sellers working on price cut it first, because nobody can see it in a photo.
- The warranty has to be honored by someone. Everything we remanufacture in house carries a one-year warranty, with 30 days on electrical components. Parts we supply as an authorized dealer carry the manufacturer’s own warranty. Either way you call us, a real shop in California, and we sort it out. A marketplace warranty usually means shipping the part overseas at your own cost and hoping for a reply.
- No core program. We credit your rebuildable core back in full. Discount sellers generally will not take one, so the gap narrows the moment you account for the core you are now stuck holding.
- Common rail has no tolerance for “close enough.” These injectors meter fuel in fractions of a millisecond at pressures north of 20,000 psi, across multiple events per stroke. A nozzle or control valve that is merely near spec will not throw a code on the bench at idle — it shows up as a cylinder that runs hot, a balance rate that drifts, fuel in the oil, or a rail pressure fault six months out. And the labor to go back in is the same as it was the first time.
We are an authorized dealer and a working fuel-injection shop — we have been rebuilding and testing this hardware in Woodland since 1993, and the people who answer the phone are the people who run the benches. Not sure this is the right part for your engine? Call us with your serial number before you order and we will confirm it. Send your rebuildable core back and the core charge is refunded. And if a price somewhere else looks too good, call 530-668-0818 and we will tell you straight whether it is a deal or a problem.
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