Navistar/International International N9, N10 DEF Head Unit
NAVISTAR/INTERNATIONAL INTERNATIONAL N9, N10 DEF HEAD UNIT
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 2321-11-3 ( OEM Part Number 4097721 ).This part is primarily made for a International N9, N10, production years 2016-2020, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: QLS DEF Header, 297mm
OEM NUMBERS
| Primary OEM | 4097721 |
| Additional OEM | 2515990C1, 2515990C3, 4087159C91, 4097721, 4097721C91, 4163689C91, 4254212C91, 4353000C92 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490541054 |
| WEIGHT | 8.00 LBS |
SHIPPING OPTIONS
Ship Weight : 8.00 LBS
UPS Ground, 2nd Day Air, Next Day Air
SHIPPING POLICY
Tamerx Diesel Products ships via UPS Ground. Next day air shipping can be arranged for a reasonable price of anywhere from $50.00 - $100.00 depending on the weight of the product and your location. We will do everything we can to make sure that you get the service you need. We understand how important it is to receive your order as quickly as possible.
In most cases Tamerx Diesel Products only needs one address, as long as your product is shipping to the same location as your billing information. In order to eliminate credit card fraud, your billing information must match the credit card you provide.
The terms, conditions, and details of our warranty vary from product to product. Specific warranty details can be found below.
Tamerx Diesel Products provides a replacement warranty on all of our parts. The duration and mileage limitations of the warranty vary by product and are specified on the product's detail page/item listing.
Please note that the warranty covers replacement of the part and the cost of shipping the replacement part to you only. It does not cover any shop, labor, towing, or any similar or related costs. This is not a "money back guarantee".
If you experience a problem with your part or it is not functioning properly, the correct warranty procedure is to call us at (510) 257-1777 (8:00 AM - 5:00 PM ET Monday through Friday). Be sure to have your order number and/or other relevant order information ready so we can easily locate your order and resolve your issue as quickly as possible. From that point, we will review with you any troubleshooting steps that may need to be taken and other areas or systems that can be checked to rule out external problems contributing to your part's issue. If a replacement is determined to be necessary, we will then arrange for your replacement part to ship out ASAP and issue any necessary return shipping labels and/or documents.
As is the case for the majority of the diesel products sold on Tamerx Diesel Products, your part's warranty is active as soon as you install it. In some other cases, warranty activation is contingent upon you sending us your core (i.e., your old part). Tamerx Diesel Products will provide you a return shipping label for parts that have a warranty with a core return condition. When we have received your core return, the part's warranty coverage begins. We reserve the right to void the product warranty if your core is not received within the allotted time, or if it isn't received at all. If the warranty for the diesel part you are purchasing has a core return requirement, it will be clearly noted on the product detail page/item listing.
What is a Core Charge?
A core charge (also called "core deposit") is similar to the deposit you might pay for a can or bottle of soda and is a standard requirement in the auto parts industry. For example, in many states, to promote recycling, you pay a deposit when you purchase a can of soda and receive your deposit back when you return the empty can. Many automotive parts have a core charge, or core price, that works in essentially the same way as a soda can deposit.
30 Day Core Charge Hold
You authorize Tamerx Diesel Products, to hold your credit card for the specified core charge amount and that you agree to return your core with 30 days of receiving the purchased part. When we have received your core return, the hold is released and the core charge payment is canceled.
The customer, or parts buyer, is responsible for any shipping costs associated with core returns unless otherwise specified in the product listing/detail page. Tamerx Diesel Products offers prepaid UPS shipping labels (SKU numbers UPS-CR1 and UPS-CR2) for use in returning your core that are available for purchase on our website during your shopping/order process.
The shipping label you will need to use for the core return is dependent upon what part you are purchasing. UPS-CR1 is good for cores weighing up to 20 pounds. UPS-CR2 is appropriate for shipping cores weighing 21 pounds or more. You must include enough information with the core return that clearly identifies it as a.) a Core Return, and b.) contains enough information we can use to clearly associate the core return with your order. Including a copy of the invoice or packing slip that came with the original shipment, clearly marked "Core Return", is ideal. Alternately, you can include a note marked as "Core Return" that includes your order number, full name and address, and phone number or other contact information. Failure to include this information with your returned core will most likely delay any due core credit being issued and/or delay any applicable warranty activation. Core returns need to be for the exact part purchased and cannot be damaged. Substituting another part in place of the part you have purchased is not acceptable.
All fluids must be drained.
If you have purchased a set or a parts package, you will need to return cores for all components of the set. For example, if you have purchaed a high pressure oil pump with an IPR valve, you will need to return both HPOP and IPR valve cores to receive proper credit. If you have purchased an EGR cooler/EGR valve package, your core return must consist of an EGR cooler core and an EGR valve core, or core credit will not be given.
Core Charges are often mandated by state legislature, and, as such, the actual core charge and taxes on the charge may vary depending on the state in which you buy your part. The Tamerx Diesel Products core charge presented to you online today with your item is representative of the most common core charge.
The Navistar/International N9, N10 DEF Head Unit: OEM 4097721 provides precise monitoring and reliable performance for the diesel exhaust fluid system in compatible Navistar engines. Built to OEM specifications, this unit measures DEF level, temperature, and quality to maintain emissions compliance and consistent aftertreatment operation. Its rugged construction ensures durability in demanding environments, protecting both the exhaust system and overall engine efficiency. Choosing an OEM DEF head unit reduces compatibility risks and supports dependable long-term reliability. This component is a trusted solution for keeping Navistar Cummins-powered trucks and equipment operating smoothly and without interruption.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2016 | International | N9 | N10 | |||
| 2017 | International | N9 | N10 | |||
| 2018 | International | N9 | N10 | |||
| 2019 | International | N9 | N10 | |||
| 2020 | International | N9 | N10 | |||
PEOPLE ALSO ASKS | BLOG(S)
The DEF Head Unit OEM 4097721 is part of the emissions aftertreatment system in International/Navistar vehicles with N9 or N10 engines. It is often called a sensor‑head or header unit and is mounted on the Diesel Exhaust Fluid (DEF) tank. It consolidates several functions into one component to manage DEF supply, state, and flow.
Key Functions in the System
- DEF Fluid Level Monitoring
- The unit includes a level sensor that detects how much DEF is in the tank. It sends that information to the engine control module (ECM) so your vehicle can alert you when DEF is low, and avoid system faults or derates.
- Fluid Temperature Sensing
- It monitors the temperature of the DEF fluid. Because DEF can freeze or become less effective in cold conditions, this allows the system to compensate — either via heating or by adjusting how the DEF is dosed.
- Clean Fluid Supply / Filtering
- The head unit has an internal filter or screen to remove particulates, debris, or possible contamination before the DEF is drawn from the tank. Clean fluid protects downstream parts like the dosing or SCR (Selective Catalytic Reduction) modules.
- Fluid Routing (Suction & Return Paths)
- It provides the connectors (suction and, in some designs, return) for DEF fluid to flow out of the tank toward the injector/dosing module, and for unused fluid to return. Proper flow and plumbing avoid air pockets, ensure correct pressure, and maintain steady dosing.
- Sensor Feedback to ECM
- All the sensor signals (level, temperature, maybe fluid quality) are sent back to the ECM. If any readings are out of range (too low level, too cold, etc.), the ECM can trigger warning lights, adjust engine/timing or reduce performance as needed to protect the system and maintain emissions compliance.
If the DEF head unit works properly, it helps your engine remain compliant with emissions standards, avoids warning codes or engine derate, and ensures the SCR aftertreatment system gets the right amount of clean DEF when needed. If it fails or gives faulty readings, you could experience decreased engine performance, higher emissions, or damage to downstream components.
Keeping this head unit in good condition is essential for reliable operation, avoiding maintenance hassles, and ensuring your Navistar vehicle stays road‑legal in terms of emissions.
The DEF (Diesel Exhaust Fluid) head unit is responsible for measuring fluid level, temperature, and quality inside the DEF tank. This data ensures the emissions system operates properly. When the head unit goes bad, it often causes system confusion, alerts, or even loss of drivability.
Common Signs of a Bad DEF Head Unit
Here’s what to look for if your DEF head unit is failing:
- Incorrect DEF level readings
- The dashboard may show full or empty when the actual level is different.
- Frequent warning messages
- Alerts like “Service DEF System” or “DEF Quality Poor” may show up repeatedly.
- Unexpected engine derates
- The vehicle might reduce speed or throttle due to false readings.
- Check engine light
- Fault codes related to DEF temperature, fluid level, or sensor communication may be stored.
- Inconsistent DEF usage
- You may notice unusual fluid consumption without any change in operation.
- Sensor signal loss
- Diagnostic tools may show missing or erratic signals from the DEF tank.
If you experience these signs, it’s best to perform a full system scan and inspect connectors. In most cases, replacement of the head unit is the solution.
It ensures accurate DEF monitoring to prevent unnecessary downtime and power loss.
Yes, a defective unit can cause failed emissions tests and costly repairs.
Verify your current DEF head unit’s part number matches OEM 4097721.
It transmits DEF tank data to the engine computer to ensure the SCR system works correctly.
International DEF Head Units
