Terex Cummins ISL DEF Head Unit
TEREX CUMMINS ISL 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 5410-11-FC01-3 ( OEM Part Number 37346 ). This part is primarily made for a Cummins ISL, 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 | 37346 |
| Additional OEM | 34809, 37346 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490540422 |
| 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.
Engineered for Terex equipment powered by Cummins ISL engines, the DEF Head Unit OEM 37346 is designed to ensure reliable Diesel Exhaust Fluid system performance and emissions compliance. This genuine OEM component is built to factory specifications, providing precise fitment and dependable operation in demanding construction and industrial environments. By maintaining proper DEF flow and system monitoring, it helps support consistent engine operation and environmental efficiency. Its durable construction is made to withstand the heavy-duty conditions of daily equipment use, delivering long-lasting reliability. For operators and fleet professionals, this DEF head unit offers OEM-certified quality and trusted performance that keeps Terex machinery running at its best.
PEOPLE ALSO ASKS | BLOG(S)
When Terex machines are powered by the Cummins ISL engine, emission control is handled through a SCR (Selective Catalytic Reduction) system. The DEF Head Unit (OEM 37346) is a key component in this system. Its primary role is to manage and monitor the Diesel Exhaust Fluid (DEF) supply so the engine’s emission strategy can function accurately and reliably.
Core Responsibilities
- DEF Level Monitoring
- The head unit constantly measures how much DEF remains in the tank and informs the engine control module (ECM) when fluid levels are low, enabling timely refills.
- Temperature Sensing / Protection
- It tracks the temperature of the DEF, helping detect when the fluid is at risk of freezing or becoming ineffective due to extreme heat, so the system can take preventive actions.
- Fluid Routing & Header Role
- As the “header,” it provides the ports and channels that route DEF from the tank to the dosing system and often return unused fluid back to the tank for circulation balance.
- Filtration & Protection
- It includes internal filtration (like strainers or screens) to prevent particles, crystals, or contaminants from reaching sensitive parts of the DEF injection system.
- Signal Communication
- The head unit relays sensor data (level, temperature, status) to the ECM or DEF controller. The control module then uses this data to properly manage DEF dosing, trigger system diagnostics, or respond to faults.
In essence, the OEM 37346 head unit is the sensor, fluid router, and communications node of the DEF tank. It ensures the SCR system knows the condition of the fluid, can deliver it properly, and can protect itself from errors—helping keep the engine clean, efficient, and compliant.
The DEF (Diesel Exhaust Fluid) Head Unit is a vital part of your vehicle’s emissions system. It measures DEF level, quality, and temperature — ensuring your truck meets emissions standards and avoids derate mode. When this component fails, many drivers ask: Can it be repaired instead of replaced? Unfortunately, the short answer is no — a DEF Head Unit is not repairable.
Why a DEF Head Unit Can’t Be Repaired
The DEF Head Unit is a sealed electronic component that houses sensitive sensors and circuitry. Once these internal parts fail or become contaminated, they cannot be accessed or serviced without damaging the unit.
Common Causes of DEF Head Unit Failure:
- Contaminated DEF fluid
- introducing debris or crystallization
- Moisture intrusion
- damaging internal electronics
- Extreme heat or freezing
- causing internal sensor failure
- Aging and wear
- from long-term use
Replacement Is the Only Reliable Solution
Because the DEF Head Unit cannot be opened or recalibrated, replacement is the only effective fix. Installing a new OEM-quality unit restores proper system communication and prevents false readings, fault codes, or derate mode.
How to Prevent Future Failures
- Use only fresh, certified DEF fluid to avoid contamination.
- Keep DEF containers sealed and clean.
- Avoid exposing the DEF system to extreme temperatures.
- Inspect the system regularly for crystallization, buildup, or corrosion.
A DEF Head Unit is not repairable or serviceable due to its sealed design and sensitive internal sensors. If yours fails, replacing it with a new OEM unit is the only safe and reliable way to restore proper emissions system function and keep your truck running smoothly.
Yes, a damaged or dirty sensor inside the unit can cause inaccurate DEF level signals.
Codes such as SPN 3364, SPN 1761, or SPN 3031 often point to DEF sensor or communication faults.
Yes, corroded or loose electrical connections can interrupt signal transmission to the ECM.
Use a diagnostic scan tool to check live sensor data and verify communication with the ECM.
Cummins DEF Head Units
