The Cummins QSB engine platform, widely used in off-highway and industrial applications, employs advanced emissions systems to meet Tier 4 Final standards. A key part of this system is the DEF Doser Injector, responsible for injecting Diesel Exhaust Fluid (DEF) into the exhaust stream to support the Selective Catalytic Reduction (SCR) process. The correct OEM part for model years 2018 to 2021 is 5506856.
This injector ensures accurate DEF atomization, which is critical for effective NOx reduction and reliable system operation.
Core Features of the OEM 5506856 DEF Doser Injector:
- Fine Mist Atomization Tip
- Ensures efficient DEF distribution into the exhaust.
- Heat-Resistant Body
- Withstands high exhaust temperatures without warping.
- Integrated Connector Port
- Links with the DEF dosing module for precise control.
- Sealing Surface and Mount Flange
- Prevent leaks and ensure proper orientation.
- Backflow Protection
- Prevents exhaust gases from entering the DEF line.
This injector is specifically calibrated for the QSB platform’s flow rates and emissions strategy. Proper function depends on using clean DEF, routine system flushing, and correct torque during installation. Replacing the injector with OEM 5506856 helps maintain regulatory compliance and prevents SCR-related error codes or malfunctions.