Cummins QSB 4.5L NOx Sensor 2018-2024: OEM 4384394

Accurate Exhaust Feedback for Cummins QSB 4.5L Systems (2018–2024)

What is it?
The Cummins QSB 4.5L NOx Sensor, referenced as OEM 4384394, is a key emissions-monitoring sensor used on Cummins QSB 4.5L diesel engines built from 2018 through 2024. Installed in the exhaust/aftertreatment stream, this sensor measures nitrogen oxide (NOx) levels and sends that information to the engine control unit. The ECU uses this data to guide aftertreatment decisions and keep emissions functions operating as intended.

Why choose this NOx Sensor?
Aftertreatment systems rely heavily on sensor feedback to determine how the SCR system responds during operation. This sensor is designed to align with Cummins factory specifications for the QSB 4.5L platform, supporting correct fitment and dependable signal output. When NOx readings become unreliable due to sensor wear or failure, the system may react incorrectly—potentially resulting in DEF dosing issues, warning indicators, or inconsistent emissions behavior. Using the correct OEM-specified NOx sensor helps maintain stable system communication and coordinated exhaust treatment.

Key Benefits
✅ Correct match for Cummins QSB 4.5L engines (2018–2024)
✅ Provides real-time NOx measurement for emissions decision-making
✅ Supports proper SCR function and DEF control logic
✅ Direct replacement fit—no modifications or adjustments needed
✅ Built to operate in high-temperature exhaust environments

Applications
This NOx sensor is used in a wide range of equipment powered by Cummins QSB 4.5L engines from the 2018–2024 model years. It’s commonly installed in commercial vehicles, work trucks, agricultural machines, industrial equipment, and generator applications where emissions monitoring is required for consistent aftertreatment operation.

Installation Notes
Let the exhaust system cool completely before servicing. Disconnect the electrical connector from the existing sensor and remove it from its mounting location. Inspect the wiring harness and sensor port for corrosion, soot buildup, or damage prior to installation. Install the replacement sensor, torque it to specification, reconnect the harness, then clear fault codes and confirm correct sensor readings using diagnostic tools.

Final Thoughts
If your Cummins QSB 4.5L-powered equipment is showing NOx-related fault codes or acting inconsistently within the emissions system, replacing the NOx sensor with the correct OEM unit can help restore accurate exhaust feedback. The Cummins QSB 4.5L NOx Sensor (OEM 4384394) plays an essential role in maintaining reliable emissions monitoring and smooth aftertreatment coordination.