Cummins DEF Head Unit : OEM ASP-908-2321-623
CUMMINS DEF HEAD UNIT : OEM ASP-908-2321-623
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a New, DuraWRX DEF Head Unit, DuraWRX part number ASP-908-2321-623 ( OEM Part Number ASP-908-2321-623 ). This part is primarily made for a Cummins , and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: DEF Header
OEM NUMBERS
| Primary OEM | ASP-908-2321-623 |
| Additional OEM | 2510966C1, 2510966C3, 2515986C1, 2515987C1, 2517604C1, 2523591C91, 4086046C91, 4097728C91, 4140918C91, 4254210C91, 4352100C92, ASP-908-2321-623 |
ADDITIONAL DETAILS
| CONDITION | New |
| UPC / Barcode | |
| WEIGHT | 7.00 LBS |
SHIPPING OPTIONS
Ship Weight : 7.00 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 OEM ASP-908-2321-623 Cummins DEF Head Unit is a critical component designed to monitor and manage diesel exhaust fluid within emission control systems. Built to precise OEM specifications, it ensures accurate communication of fluid levels and temperatures, supporting compliance with environmental standards. Its design allows for proper integration with compatible Cummins systems, providing dependable operation and a secure fit. The durable construction helps the unit withstand harsh conditions and deliver consistent results over time. With this OEM DEF head unit, operators can rely on
PEOPLE ALSO ASKS | BLOG(S)
The DEF Head Unit, OEM part number ASP‑908‑2321‑623, is a vital Digital (CAN-bus) DEF header module designed for Cummins applications—particularly Navistar/International engines (such as the QSX15) that utilize aftertreatment systems.
Key details:
- Sensor Type
- Digital (CAN-bus) for accurate data transmission to the engine control system.
- Electrical Connector
- Deutsch DT4 standard connector.
- Header Height
- 25 inches, featuring an in-tank DEF header with built-in filtration (40 µm strainer).
- Fluid Connections:
- DEF suction: 3/8-inch SAE J2044
- DEF return: 5/16-inch SAE J2044
- Coolant inlet: 5/8-inch hose bead
- Mounting
- 6-bolt tank interface ensures secure installation.
- 6-bolt tank interface ensures secure installation.
It cross-references a series of OEM replacement numbers, including (but not limited to): 4352100C91, 2523591C91, 4140918C91, 4097728C91, 4254210C91, 2517604C1, 4086046C91, 2515986C1, and 2515987C1.
Why It Matters
The DEF Head Unit integrates essential components—like sensors for level, temperature, and quality—with filtration and fluid interfacing in one assembly. This design streamlines the SCR system, promoting accurate DEF dosing and easier maintenance.
It is offered by aftermarket supplier DuraWRX under the same part number and typically comes with a One Million Miles or One Year Warranty, granting added confidence in product longevity and reliability.
The DEF (Diesel Exhaust Fluid) Head Unit—also called a DEF quality sensor or sending unit—is responsible for monitoring DEF level, temperature, and quality in the tank. It's a critical part of the emissions system, and when it starts to fail, it can cause major drivability issues and system warnings.
Common Symptoms of a Failing DEF Head Unit
1. Inaccurate DEF Level Readings
If your gauge suddenly reads empty or full with no recent refill or usage, the DEF head unit may be sending faulty data to the ECM.
2. “Incorrect DEF Quality” or “Poor Fluid Detected” Warnings
When the sensor misreads urea concentration, it may falsely trigger warnings—even if the fluid is clean and certified.
3. Check Engine Light or Malfunction Indicator Lamp (MIL)
A bad sensor often sets off emissions-related DTCs (e.g., P203F, P206A, P207F), which are picked up by diagnostic tools.
4. DEF System Fault or Derate Warnings
A failing DEF head unit can lead to emissions derates that restrict engine speed or eventually prevent the engine from restarting.
5. Inconsistent DEF Temperature Readings
Cold weather faults or failed heating elements in the head unit can result in a frozen tank that doesn’t thaw as expected.
Steps to Confirm Failure
- Scan the system for codes
- Use a diagnostic tool to identify codes related to the DEF system or sensor.
- Compare live data
- Look at temperature, level, and quality readings in real-time. Fluctuating or unrealistic values indicate sensor trouble.
- Inspect for contamination
- Crystallized DEF or debris in the tank can damage the sensor and produce erratic readings.
- Test with known good fluid
- If you’ve recently changed the DEF and still get poor quality warnings, the issue is likely with the head unit—not the fluid.
Important Considerations
- Most DEF head units are non-serviceable, meaning they cannot be repaired individually. If one part fails, the entire module may need replacement, often requiring full DEF tank replacement.
- Some units are subject to OEM extended warranties or recalls, especially on medium and heavy-duty vehicles. Check with the manufacturer or dealer for coverage options.
If you're seeing DEF-related warnings, erratic gauge readings, or emissions-related faults, a failing DEF head unit may be the cause. Prompt diagnostics can prevent downtime and avoid entering restricted operation modes. If you need help narrowing down specific codes or replacement procedures for your unit, I can assist further—just let me know the vehicle make and model.
It ensures accurate DEF monitoring, supporting emissions compliance and system reliability.
DEF low-level, quality, or temperature errors often point to head unit failure.
Troubleshooting involves checking wiring, fluid levels, and fault codes related to DEF.
Yes, it is designed to operate in harsh temperature and road conditions.
Cummins DEF Head Units
