Cummins QSB 4.5L Dosing Module 2018-2024: OEM 4394644

Emissions Fluid Dosing Module for Cummins QSB 4.5L Engines (2018–2024)

What is it?
The Cummins QSB 4.5L Dosing Module (2018–2024), identified by OEM part number 4394644, is a core component of the selective catalytic reduction (SCR) system used on Cummins QSB 4.5-liter diesel engines produced between 2018 and 2024. This module controls the delivery of Diesel Exhaust Fluid (DEF) into the exhaust stream, allowing the SCR system to convert nitrogen oxides (NOx) into harmless nitrogen and water before the gases exit the system.

Why choose this Dosing Module?
Built to Cummins’ original equipment specifications, this DEF dosing module ensures accurate fluid delivery in response to real-time engine and emissions system demands. When the dosing module is worn, clogged, or malfunctioning, improper DEF delivery can lead to elevated NOx readings, aftertreatment warnings, or less efficient SCR performance. Using the correct OEM-specified dosing module supports coordinated emissions responses and more stable SCR behavior.

Key Benefits
✅ Designed for Cummins QSB 4.5L aftertreatment systems (2018–2024)
✅ Precisely regulates DEF delivery for optimal NOx conversion
✅ Supports coordinated operation with sensors and SCR control logic
✅ Direct replacement — no modifications required
✅ Built for reliable performance in heavy-duty environments

Applications
This dosing module is ideal for medium- and heavy-duty vehicles powered by Cummins QSB 4.5L engines manufactured from 2018 through 2024. Examples include commercial trucks, vocational equipment, agricultural machinery, and industrial generators where accurate DEF metering is critical to emissions control and compliance.

Installation Notes
Before servicing, ensure the aftertreatment system and exhaust components are fully cooled. Disconnect the electrical connection to the existing dosing module, then remove it from its mounting bracket. Inspect wiring and mounting surfaces for signs of wear or corrosion before installing the replacement. Install the new module using proper fasteners and ensure all electrical connectors are secure. After installation, clear any stored fault codes and verify proper DEF delivery using diagnostic tools.

Final Thoughts
If your Cummins QSB 4.5L-equipped vehicle is showing emissions warnings, elevated NOx readings, or inconsistent aftertreatment behavior, replacing the dosing module with the correct OEM-specified unit can help restore coordinated DEF metering and more predictable system performance. The Cummins QSB 4.5L Dosing Module (OEM 4394644) plays an essential role in maintaining regulated exhaust treatment and dependable engine operation across varied duty cycles.