Navistar/International International N9, N10 DEF Head Unit

Clean DEF Monitoring for Navistar N9 / N10: OEM DEF Head Unit (4097721), 2016‑2020

What is it?
The OEM 4097721 DEF Head Unit is a factory-specified DEF (Diesel Exhaust Fluid) header assembly designed for Navistar/International N9 and N10 engines from model years 2016‑2020. This unit includes the sensor head unit which monitors DEF fluid level, temperature, and interfaces with QLS (Quiet Level Sensing) systems to help maintain proper SCR emissions performance.

Why choose this OEM DEF Head Unit?
Built to exact OEM International/Navistar standards, this head unit delivers precise sensor functionality, correct sealing, and unaltered compatibility with DEF systems. Using the genuine part helps avoid warning lights, faulty level readings, or malfunctions often seen with non‑OEM or off‑spec units.

Key Benefits
 ✅ Direct OEM fit for Navistar/International N9 & N10 engines (2016‑2020)
 ✅ Provides accurate DEF fluid level and temperature sensing under QLS systems
 ✅ Correct sealing to prevent leaks and maintain DEF fluid integrity
 ✅ Reduces risks of false fault codes and system derates
 ✅ Built for long service life under vehicle vibration, thermal stress, and road conditions

Applications
Ideal for Navistar / International trucks equipped with N9 or N10 diesel engines that use DEF & QLS systems. Commonly used in vocational, regional, and highway applications where emissions compliance and reliable DEF performance are essential.

Installation Notes
Have the installation done by certified technicians. Depressurize or isolate the DEF system first. Clean the DEF tank opening and replace any seals/O‑rings. Install the head unit per OEM torque specs. After installation, verify correct sensor output and clear any DEF system warning or fault codes.

Final Thoughts
If your N9 or N10 is showing DEF tank warning lights, erratic level sensor readings, or you’re servicing the DEF system, replacing the head unit with the OEM 4097721 component restores accurate monitoring, sealing, and emission control—all with factory‑matched reliability.