Cummins B6.7, L9 SCR 2018-2021: OEM 5418679

Reliable NOx Conversion for Cummins B6.7 & L9 Engines (2018–2021)

What is it?
The Cummins B6.7/L9 SCR (Selective Catalytic Reduction) assembly, designated by OEM part number 5418679, is an emissions aftertreatment component used on Cummins B6.7 and L9 diesel engines manufactured between 2018 and 2021. It operates as part of the selective catalytic reduction system, using Diesel Exhaust Fluid (DEF) to help convert nitrogen oxides (NOx) in the exhaust into nitrogen and water before the gases exit the system, contributing to regulated emissions control.

Why choose this SCR Assembly?
This SCR module is built to Cummins’ original specifications for both B6.7 and L9 engine platforms, ensuring a precise fit and consistent integration with DEF dosing hardware, emissions sensors, and engine control systems. Over time, SCR effectiveness can diminish due to normal wear or contamination, which may impact NOx conversion and trigger emissions alerts. Choosing the correct OEM-specified assembly helps maintain dependable emissions control and coordinated aftertreatment performance.

Key Benefits
✅ Designed for Cummins B6.7 and L9 aftertreatment systems (2018–2021)
✅ Supports dependable NOx conversion with DEF interaction
✅ Helps sustain coordinated operation with related emissions components
✅ Direct-fit replacement — no modifications required
✅ Constructed for heavy-duty exhaust environments

Applications
This SCR assembly fits medium- and heavy-duty trucks and commercial vehicles equipped with Cummins B6.7 or L9 engines built between 2018 and 2021. Common applications include delivery fleets, vocational trucks, regional transport rigs, and other commercial platforms where reliable emissions control and regulatory compliance are part of daily operations.

Installation Notes
Before servicing, ensure the exhaust and aftertreatment system has cooled completely. Remove the existing SCR module and inspect adjacent DEF lines, sensors, and mounting hardware for signs of soot buildup, wear, or damage. Install the replacement unit using proper seals and fasteners to ensure a secure, leak-free fit. After installation, clear any stored system codes and verify correct SCR operation with diagnostic tools.

Final Thoughts
If your Cummins B6.7 or L9-equipped vehicle is showing NOx-related warnings, inconsistent emissions readings, or uneven aftertreatment behavior, replacing the SCR assembly with the correct OEM-specified component can help restore balanced emissions control and smoother system responses. The Cummins B6.7/L9 SCR (OEM 5418679) plays a key role in managing regulated exhaust chemistry and supporting dependable vehicle use across varied duty cycles.