Product Description
Fix the LML’s CP4 weak link—permanently. The INDUSTRIAL INJECTION 436401 CP4-to-CP3 Conversion Kit for 2011–2016 GM 6.6L Duramax LML replaces the failure-prone CP4.2 with a proven CP3 (pump included). This factory-fit kit is designed to run on stock calibration with no tuning required while retaining factory emissions equipment when installed as directed.
Fitment
- 2011–2016 Chevrolet/GMC 2500HD & 3500HD — 6.6L Duramax LML
What’s Included
- New CP3 high-pressure pump (LBZ-based)
- Application-specific brackets, lines/adapter components, and hardware
- Electrical provisions/harness extensions for OE-style integration
- Installation instructions
Why Convert?
- Reliability: CP3 is widely regarded as more durable than CP4 in stock and tuned use.
- No Tuning Required: Designed to operate with factory calibration on emissions-intact trucks.
- Factory-Fit: Clean install without custom fabrication.
Recommended Parts (CPP Internal Links)
- FASS DMAX7002 Lift Pump (2011–2016 LML) — improves filtration and CP3 supply pressure.
- Fleece Auxiliary Heated Fuel Filter Kit (LML) — upgraded filtration & water management.
- Dorman 904-000 Fuel Filter Housing (LML) — fresh filter head if yours seeps/air-leaks.
- S&S 50-State CARB-Legal CP3 Conversion (W/ Pump) — alternate CARB-exempt option.
- Shop All GM Duramax Parts
Helpful Notes
- Intended for emissions-intact trucks; follow instructions to retain OE aftertreatment.
- Adding a quality lift pump and upgraded filtration extends CP3 life and helps rail pressure stability.
- After install, clear any CP4-related DTCs and perform standard fuel system priming/bleed procedures.
FAQ
Do I need custom tuning with this kit?No. This kit is engineered to operate on the factory calibration for emissions-intact LML trucks.
Is the CP3 pump included?Yes. This is the with-pump version; a brand-new CP3 is included along with brackets, lines/adapters, and hardware.
Will this pass emissions?The kit is designed to be used with all factory emissions equipment retained and functioning. For a CARB-exempt option, consider our S&S 50-state kit linked above.
What maintenance is recommended after converting?Use high-quality fuel, change filters on time, and consider a lift pump and auxiliary filtration to protect the CP3 and injectors.
