The part number 5579421 refers to a Fuel Injector used in the Cummins X15 engine series (as well as the preceding ISX15).
Here is the detailed breakdown of what this part is, its specifications, and its applications.
1. Part Identification
Part Number: 5579421
Part Type: Fuel Injector (Diesel)
Manufacturer: Cummins Inc.
Condition: This number typically represents a Cummins ReCon (Remanufactured) injector. If you are looking for a brand-new OEM injector, the core number often falls under 4327330 or 4327331 (depending on the specific trim/code), but 5579421 is the commonly sold service part number for the reman unit.
2. Specifications
These injectors are High-Pressure Common Rail (HPCR) injectors. Unlike older mechanical injectors, these are electronically actuated and hydraulically amplified.
Type: HPCR (High Pressure Common Rail)
Flow Rate: Designed for X15 engines typically rated between 400 and 600 horsepower.
Body Style: Standard X15/ISX15 body with a specific "spill control valve" design.
Torque Specs:
3. Engine Application
This injector is compatible with the following engine families:
Cummins X15 (2016–Present) – Productivity Series, Efficiency Series, and Performance Series.
Cummins ISX15 (2010–2016) – Specifically models built to meet GHG14 (Greenhouse Gas) and EPA10 emissions standards.
4. Important Buying & Installation Notes
If you are purchasing or installing this part, there are three critical factors to consider:
A. Trim Code Calibration
X15 injectors are graded by "Trim Codes." When replacing injectors, you must program the new injector's trim code into the Engine Control Module (ECM) using Cummins INSITE software. Failing to do so will result in rough idling, misfires, and potential engine damage.
B. The "Injector Kit"
Often, when purchasing injector number 5579421, you may actually need the installation kit. Ensure you have:
Gasket Kit: 4329168 (Includes copper seal, o-rings, and backup rings).
Hold Down Bolt: It is highly recommended to replace the hold-down bolt (Part # 3681973) as they are torque-to-yield (stretch) bolts.
5. Common Failure Symptoms
If you are replacing these, the common failure modes for X15 injectors include:
Rough idle (especially when hot).
Excessive white smoke on startup (indicating fuel dilution in oil or stuck injector).
Misfire under load (often caused by worn spill valve or stuck plunger).
Where to buy：
Rsolid is a professional diesel injector manufacturer that relies on the precision manufacturing capabilities of its own factories to provide high-quality solutions for the global commercial vehicle, construction machinery, marine, and agricultural diesel engine markets. Rsolid's business model typically includes maintaining a diverse and comprehensive OEM and high-end aftermarket parts inventory, and providing cross compatibility options to meet the needs of various applications and global customers, from individual workshops to large fleet operators. If you are looking for diesel injectors or OEM engine injectors, please feel free to contact us at any time.
