Refresh Aftertreatment Flow on Cummins L9 (2018–2021)
What is it?
The Cummins L9 SCR OEM 4394878 is a key emissions aftertreatment component designed to help reduce nitrogen oxide (NOx) emissions from your diesel engine’s exhaust. Working in tandem with the diesel exhaust fluid (DEF) system, this SCR assembly supports the conversion of harmful exhaust gases into cleaner compounds before they exit the vehicle, helping maintain emissions compliance and supporting stable engine performance.
Why choose OEM 4394878?
This SCR assembly is built to Cummins’ factory specifications for L9 engines produced from 2018 through 2021. Engineered for precise integration with the original aftertreatment system, it helps minimize the risk of emissions-related fault codes, warning lights, and engine derates. Choosing an OEM-matched component ensures compatibility with your engine’s design and reliable performance over time.
Key Benefits
✅ Designed for Cummins L9 engines (2018–2021)
✅ Helps support effective NOx reduction with DEF
✅ Aids in reducing emissions system alerts
✅ Built to withstand high exhaust temperatures and daily use
✅ Direct-fit design for a smoother installation
Applications
This SCR assembly is ideal for on-highway trucks, vocational vehicles, and commercial fleets powered by Cummins L9 engines from 2018–2021. It’s commonly used in delivery rigs, service trucks, and other diesel-powered equipment that require dependable emissions control.
Installation Notes
Before beginning installation, allow the exhaust system to cool completely. Inspect related sensors, clamps, gaskets, and mounting hardware, and replace any worn parts as needed. Once installed, verify all connections are secure and follow manufacturer-recommended system checks or resets.
Final Thoughts
If emissions performance issues arise on your Cummins L9 engine, the OEM 4394878 SCR assembly provides a reliable, factory-aligned replacement solution. With proper fitment and consistent operation, it helps keep your vehicle compliant and ready for the road. Tamerx has this SCR assembly in stock and ready to ship.