4097727C91 | Genuine OEM International DEF QLS 15.5G/23G Header

The Genuine OEM International / Navistar 4097727C91 DEF Quality Level Sensor (QLS) Header is designed for compatible commercial diesel trucks equipped with 15.5-gallon, 16-gallon, or 23-gallon Diesel Exhaust Fluid (DEF) tanks. This DEF tank header assembly monitors fluid level, quality, and temperature to support the vehicle's Selective Catalytic Reduction (SCR) emissions control system.

Designed for compatible International / Navistar applications, the 4097727C91 DEF header provides essential DEF system information to the vehicle's electronic controls, helping maintain proper emissions system operation.

PRODUCT INFORMATION

• Part Number: 4097727C91

• Brand: International / Navistar

• Condition: Not specified

• Component: DEF Quality Level Sensor Header

• Part Type: DEF Tank Head Unit / QLS Sensor Assembly

• Sensor Technology: Ultrasonic QLS

• Tank Capacities: 15.5, 16, and 23 Gallons

• System: Diesel Exhaust Fluid (DEF) / Selective Catalytic Reduction (SCR)

• Sensor Functions: DEF Level, Quality, and Temperature Monitoring

• Communication: Digital Sensor Interface

• Electrical Connector: Verify against original assembly

• Installation Location: DEF Tank

• Application: Heavy-Duty Commercial Diesel Trucks

• Fuel Type: Diesel

• Engine Applications: Selected Cummins ISX15 / X15 and Navistar N13 configurations

• Vehicle Applications: Selected International / Navistar trucks

• OEM Service References: 4254216C91, 4163695C91

• Remanufactured Reference: 5012174R91

• Fitment Period: Selected 2017–2024 applications; verify by VIN

APPLICATIONS

The International 4097727C91 DEF Header is intended for compatible International / Navistar commercial vehicles equipped with the appropriate DEF tank and SCR emissions system.

Potential applications include:

• International ProStar

• Selected International / Navistar Heavy-Duty Trucks

• Commercial Trucks with 15.5-Gallon DEF Tanks

• Commercial Trucks with 16-Gallon DEF Tanks

• Commercial Trucks with 23-Gallon DEF Tanks

• Selected Cummins ISX15 / X15 Diesel Engine Applications

• Selected Navistar N13 Diesel Engine Applications

Application catalogs reference selected 2017–2024 vehicles. The original International service documentation identifies the 4097727C91 header for applicable 2016-and-newer federal emissions configurations.

Important: Tank capacity, engine model, and model year alone do not guarantee fitment. Confirm the original part number, tank configuration, sensor generation, connector, and vehicle VIN before purchasing.

FUNCTION

The International 4097727C91 DEF QLS Header is installed in the DEF tank and provides fluid-related information to the vehicle's emissions control system.

The QLS sensor monitors DEF level, quality, and temperature. This information helps the electronic control system identify DEF supply conditions and support proper operation of the SCR emissions system, which reduces nitrogen oxide (NOx) emissions.

A worn, damaged, or failing DEF QLS header may cause symptoms such as:

• Incorrect or fluctuating DEF level readings

• DEF quality or concentration warning messages

• Check engine or SCR system warning lights

• DEF sensor communication or diagnostic trouble codes

• Emissions-related engine power derating

• DEF temperature readings becoming inaccurate or unavailable

WHY REPLACE A DEF QLS HEADER?

A malfunctioning DEF quality level sensor can prevent the vehicle's emissions control system from receiving accurate DEF information.

Replacing a defective header with the correct Genuine OEM International 4097727C91 component helps restore intended DEF level, quality, and temperature monitoring.

Proper DEF header operation supports reliable SCR system diagnostics and helps prevent operating restrictions caused by faulty sensor information.

FITMENT INFORMATION

The International 4097727C91 DEF QLS Header requires verification of the complete DEF tank and emissions system configuration.

Before purchasing, confirm:

• Original OEM Part Number: 4097727C91

• DEF Tank Capacity: 15.5, 16, or 23 Gallons

• Vehicle make, model, and model year

• Engine model and emissions configuration

• DEF header sensor generation and calibration

• Electrical connector and wiring compatibility

• Tank mounting interface

• Sensor insertion length and tank depth

• DEF suction, return, and coolant connection arrangement

• Vehicle Identification Number (VIN)

• Applicable International / Navistar service replacement information

If you are unsure whether this DEF header fits your truck, please contact us with your VIN, truck model, model year, DEF tank capacity, and original part number before ordering.

Installation Note: DEF header replacement should follow the vehicle manufacturer's service procedures. Protect the DEF system from contamination, verify all electrical and fluid connections, and confirm sensor communication and SCR system operation after installation.

GENUINE INTERNATIONAL PART

International / Navistar supplies genuine replacement components for commercial diesel vehicles and emissions control systems.

The Genuine OEM International 4097727C91 DEF QLS Header is intended for compatible DEF tank configurations, helping maintain accurate fluid monitoring and proper SCR system operation when correctly matched and installed.