Oshkosh Cummins DEF Head Unit
OSHKOSH CUMMINS 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 4310-11-23 ( OEM Part Number 3350459 ). 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, 40 MICRON, 11"
OEM NUMBERS
| Primary OEM | 3350459 |
| Additional OEM | 3350459, D004R766 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490541047 |
| 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.
Dependable DEF system operation comes from the Oshkosh Cummins DEF Head Unit: OEM 3350459, a direct-fit replacement for compatible Oshkosh vehicles and equipment. Built to OEM standards, this unit tracks diesel exhaust fluid level, temperature, and quality to ensure emissions compliance and consistent aftertreatment function. Its durable design withstands demanding service conditions, helping protect the exhaust system and maintain overall engine efficiency. By choosing an OEM DEF head unit, you reduce compatibility concerns and ensure long-term reliability. This component is a proven choice for keeping Oshkosh Cummins-powered machinery running smoothly and without interruption.
PEOPLE ALSO ASKS | BLOG(S)
The DEF Head Unit with OEM number 3350459 (also listed under part “4310‑11‑23”) is a multifunction module mounted on the Diesel Exhaust Fluid (DEF) tank. It includes several sensors, filters, and fluid routing parts all integrated into a single assembly. The whole unit ensures the DEF system works cleanly, reliably, and in compliance with emission standards.
Here are the key components inside the 3350459 DEF Head Unit:
- Level Sensor
- Detects how much DEF fluid remains in the tank. Sends signals so the engine controller knows when fluid is getting low.
- Temperature Sensor
- Monitors fluid temperature to make sure DEF remains usable and hasn’t frozen or become degraded in cold conditions.
- Internal Filter (≈ 40 Micron Screen)
- Removes particulates, debris, and impurities from the DEF before it is drawn into the dosing or SCR system. Helps prevent clogging and damage downstream.
- Suction / Pickup Port
- The inlet through which DEF is drawn from the tank and delivered to the DEF dosing or injection system.
- Return Port
- Provides a path for any unused or recirculated DEF fluid to return to the tank, maintaining stable flow and preventing pressure issues or air pockets.
- Electrical Connector(s)
- Interfaces that provide power and send data from the sensors (level, temperature) to the engine control module (ECM).
- Mounting Flange / Header Body with Seals / Gasket
- The housing that mounts this head unit onto the DEF tank. Includes sealing surfaces, a gasket or O‑ring, and structural parts to ensure a leak‑free installation.
Each of these components plays a vital role in the proper functioning of the DEF system:
- Clean, correctly filtered DEF extends the life of injectors, pumps, and SCR catalysts.
- Accurate fluid level sensing avoids running dry or triggering unnecessary warnings.
- Temperature monitoring ensures the system works even in cold climates.
- Proper suction/return plumbing prevents air in the lines, maintains pressure, and ensures the correct amount of fluid is delivered.
Together, they help maintain emissions compliance, avoid engine derate or faults, and keep the emissions aftertreatment system reliable.
The DEF (Diesel Exhaust Fluid) head unit is one of the most critical components in your vehicle’s emissions system. Its job is to monitor the level, temperature, and quality of DEF fluid inside the tank. This information is sent to the engine control module, which adjusts dosing to reduce harmful emissions.
Why the DEF Head Unit Matters
A properly functioning DEF head unit ensures:
- Accurate fluid level monitoring
- Prevents running out of DEF unexpectedly
- Correct fluid dosing
- Helps the SCR (Selective Catalytic Reduction) system neutralize emissions
- Compliance with emissions standards
- Prevents violations and inspection failures
- Avoidance of derate mode
- Keeps the vehicle operating at full capability
- System reliability
- Helps prevent false warnings, unnecessary repairs, and downtime
If the DEF head unit stops working, the vehicle may show inaccurate readings, activate warning lights, or even limit speed. In some cases, it can lead to full system shutdown if not resolved.
Without a working DEF head unit, the entire aftertreatment system can’t function properly. That’s why routine inspection and prompt attention to warning signs are essential.
It measures DEF tank level, temperature, and quality in Cummins engines used in Oshkosh vehicles.
It provides accurate DEF readings to keep the SCR system operating correctly and emissions compliant.
It is mounted inside the DEF tank to directly monitor fluid conditions.
False DEF readings, fault codes, or engine derates often indicate failure.
Cummins DEF Head Units
