Cummins B6.7, L9 SCR 2018-2021: OEM 5418545

Purpose-Built NOx Management for Cummins B6.7 & L9 Engines (2018–2021)

What is it?
The Cummins B6.7/L9 selective catalytic reduction (SCR) assembly, identified by OEM part number 5418545, is an emissions aftertreatment component designed for Cummins B6.7 and L9 diesel engines produced between 2018 and 2021. Working in concert with Diesel Exhaust Fluid (DEF), this unit helps convert nitrogen oxides (NOx) in the exhaust into nitrogen and water before the gases exit the aftertreatment system, aiding emissions control across varied operating conditions.

Why choose this SCR Assembly?
This SCR module is engineered to meet Cummins’ original specifications for both the B6.7 and L9 engine platforms, ensuring proper fit and dependable integration with DEF delivery components, emissions sensors, and engine controls. When SCR parts degrade or lose effectiveness over time, NOx conversion efficiency can drop, potentially leading to emissions alerts and inconsistent aftertreatment behavior. Selecting the correct OEM-specified assembly helps preserve coordinated exhaust treatment and smoother overall system performance.

Key Benefits
✅ Designed for use with Cummins B6.7 and L9 aftertreatment systems (2018–2021)
✅ Supports consistent NOx reduction with DEF chemistry
✅ Helps maintain coordinated operation with related emissions components
✅ Direct-fit replacement — no modifications required
✅ Constructed to handle demanding exhaust temperatures

Applications
This SCR assembly is suited for medium- and heavy-duty vehicles equipped with Cummins B6.7 or L9 engines built between 2018 and 2021. It’s commonly installed in delivery trucks, vocational rigs, regional transport units, and other commercial vehicles where dependable emissions control and regulatory compliance are important to daily operation.

Installation Notes
Make sure the exhaust and aftertreatment system has cooled completely before beginning service. Remove the existing SCR assembly, and inspect adjacent DEF lines, sensors, and mounting hardware for signs of wear, buildup, or damage. Install the replacement module using appropriate seals and fasteners to ensure a secure, leak-free fit. After installation, clear any stored system codes and verify correct aftertreatment behavior using diagnostic tools.

Final Thoughts
If your Cummins B6.7- or L9-equipped vehicle is showing NOx-related warnings or uneven aftertreatment performance, replacing the SCR assembly with the correct OEM-specified unit can help restore balanced emissions control. The Cummins B6.7/L9 SCR (OEM 5418545) plays a vital role in managing exhaust chemistry and supporting reliable engine behavior across varied duty cycles.