If your diesel came with the Bosch CP4.2 high-pressure pump — 2011+ 6.7L Power Stroke, 2011–2016 LML Duramax, and 2019+ 6.7L Ram Cummins — you've probably heard about converting to the older Bosch CP3. Here's a straight look at why owners do it and what to weigh.

The problem the conversion solves

The CP4.2 is lubrication-sensitive. Under certain conditions it can score internally and shed metal throughout the fuel system, turning a pump failure into a full pump-injectors-rails-lines replacement. The CP3 — used across the 2003–2007 5.9L and 2007.5–2018 6.7L Cummins and the LB7–LMM Duramax — has a long reputation for being robust and forgiving.

Why owners convert

• Peace of mind — removing the CP4 removes the catastrophic-failure risk it's known for.
• Proven durability — the CP3 has a strong track record across many platforms.
• Headroom — CP3 setups support added fuel volume for those running more power.

What to weigh

• Cost up front vs. the cost (and risk) of a CP4 failure later.
• Emissions and warranty — understand the implications for your vehicle and how you use it.
• Kit completeness — a proper conversion includes the pump and the supporting components for your platform.

Alternatives

If you're not ready to convert, fuel lubricity additives and "disaster-prevention" kits (which bypass debris if the pump fails) are lower-cost ways to reduce risk. See our CP3-vs-CP4 guide and our CP4 failure article for the full picture.

Before you order: conversion kits and pumps are platform- and year-specific — verify the correct kit for your exact application by OEM cross-reference.

Browse our fuel injector catalog, fuel pump collection, and contamination/prevention kits, or contact us with your engine details.