Cummins QSK SCR Outlet Catalyst Module 2014-2022: OEM 4379921

Manage NOx Emissions with a Cummins QSK SCR Outlet Catalyst Module

What is it?
The Cummins QSK SCR Outlet Catalyst Module, identified by OEM 4379921, is an exhaust aftertreatment component designed for compatible Cummins QSK diesel engines produced between 2014 and 2022. It works within the Selective Catalytic Reduction (SCR) system to help convert nitrogen oxides (NOx) into less harmful substances before exhaust exits the system. Proper catalyst function helps support effective emissions treatment and consistent aftertreatment operation.

Why choose this SCR Outlet Catalyst Module?
Effective NOx conversion depends on a properly functioning SCR catalyst and the components that support the aftertreatment process. Extended heat exposure, contamination, excessive deposits, physical damage, or catalyst deterioration can reduce treatment efficiency over time. Possible signs of an SCR system issue may include emissions-related fault codes, warning lights, reduced catalyst efficiency, or engine derate conditions. Using the correct OEM-matched replacement helps maintain compatibility with the existing Cummins QSK aftertreatment system.

Key Benefits
✅ Designed for compatible Cummins QSK diesel engines (2014–2022)
✅ Helps convert and reduce NOx emissions
✅ Supports proper SCR aftertreatment operation
✅ Helps maintain consistent exhaust emissions treatment
✅ OEM-matched replacement for proper fitment

Applications
This SCR Outlet Catalyst Module is intended for compatible Cummins QSK diesel engine applications manufactured between 2014 and 2022. It is suitable for heavy-duty diesel applications that depend on effective exhaust aftertreatment during demanding and extended operating conditions. Verify OEM 4379921 against the original catalyst module and specific engine configuration before ordering.

Installation Notes
Before installation, inspect the surrounding exhaust piping, DEF dosing components, NOx sensors, clamps, seals, and mounting hardware for leaks, contamination, or damage. Diagnose any underlying engine, DEF dosing, or aftertreatment issue that may have contributed to the previous catalyst problem. Follow the appropriate Cummins service procedures, secure all connections correctly, and check for exhaust leaks and proper SCR system operation after installation.

Final Thoughts
Proper SCR catalyst operation is essential for managing NOx emissions from Cummins QSK diesel engines. The Cummins QSK SCR Outlet Catalyst Module (OEM 4379921) provides an OEM-matched replacement for compatible 2014–2022 applications, helping support effective exhaust treatment and dependable aftertreatment system function.