Exergy 11-16 Chevrolet Duramax 6.6L LML Improved Stock CP4.2 Pump
If your 2011-2016 Silverado or Sierra 2500HD/3500HD, Express or Savana with the 6.6L LML Duramax is throwing low rail pressure codes, losing power under load or has already eaten its factory CP4.2, this is a direct replacement pump that keeps the stock layout. Exergy part E04 10504 is a new CP4.2 built with changes aimed at the way the factory pump fails, and it bolts in without tuning or supporting mods.
The CP4.2 is the engine-driven high pressure pump that feeds the common rails. It pulls fuel through an inlet metering valve, which the ECM uses to control how much fuel reaches the pumping elements, and then pressurizes it for the injectors. Inside, two plungers ride on rollers that run against a cam. When fuel quality or lubricity drops, the roller can stop rolling and start skidding on the cam. That wear makes metal, and the metal travels downstream into the rails and injectors. That is why a CP4.2 failure on an LML is rarely just a pump job.
Exergy's improved stock pump goes after that failure point. The followers are pinned so the buckets cannot rotate and drag the roller across the cam, and the rollers are a larger diameter to lower stress at the cam contact and resist jamming from contamination. It also ships with Exergy's System Saver inlet metering valve installed, which replaces the factory single-layer 85 micron screen in a plastic frame with a two-layer 10 micron screen on a stainless frame, plus a heavier FPRV screen.
Scan for codes and log desired versus actual rail pressure on a hard pull. Pull the fuel filter and look at the bottom of the housing with a flashlight. Any shiny particles mean the pump has started to come apart, and the rails, lines and injectors need to be addressed at the same time. Also rule out a weak supply side: Exergy recommends roughly 150 GPH at 8-10 psi per pump for full performance. If the truck goes into limp mode with no fuel codes at all, read our Allison 1000 limp mode guide first, because the LML's six-speed can trigger the same reduced-power complaint.
Exergy lists E04 10504 for 2011 through 2016 Chevrolet Silverado 2500HD and 3500HD, GMC Sierra 2500HD and 3500HD, Chevrolet Express 2500/3500 and GMC Savana 2500/3500 with the 6.6L LML. It is listed as a direct replacement for Bosch 0 445 010 616, 0 445 010 817 and 0 986 437 421 and GM 12638262, 12645102, 12658095, 12661059 and 98077841. Check the number on your old pump against that list, or send us your year and VIN before ordering. It does not fit the 2017-up L5P, which uses a Denso HP4. You can browse other LML parts on our Allison 1000 and Duramax page.
Exergy rates this pump for stock up to around 550 horsepower. If you want to leave the CP4.2 platform entirely, compare it with a LML CP3 conversion kit.
| Brand | Exergy |
| Part number | E04 10504 |
| Fits | Exergy 11-16 Chevrolet Duramax 6.6L LML Improved Stock CP4.2 Pump |
| Vehicle fitment | Chevrolet Duramax (2011-2016) |
| Type | Injection Pumps & Controllers |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. Exergy states this improved stock CP4.2 does not require tuning or supporting modifications. It is meant as a drop-in replacement for the factory pump on stock trucks up to about 550 horsepower.
If you find metal in the fuel filter, the debris has likely reached the rails and injectors. Plan on injectors, rails, high pressure lines, filter and a tank and line flush along with the pump, or a complete LML disaster kit.
No. Exergy lists no core charge and no core return for this pump.
No. This pump is for the 2011-2016 LML only. The 2017-up L5P uses a different high pressure pump.
It is not required. Exergy recommends a supply of about 150 GPH at 8-10 psi per pump for best performance, and an in-tank lift pump is a good way to get steady feed pressure.
