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 5410-18-FC01-6 ( OEM Part Number 37340 ). 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, 18"
OEM NUMBERS
| Primary OEM | 37340 |
| Additional OEM | 34812, 37340 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490540569 |
| 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.
Built for precision and dependability, the Terex Cummins ISL DEF Head Unit, OEM part number 37340, provides accurate monitoring and regulation of Diesel Exhaust Fluid (DEF) levels, temperature, and quality within the emissions system. Manufactured to OEM specifications, this DEF head unit ensures exact fitment and reliable performance in demanding diesel environments. Constructed from high-quality, corrosion-resistant materials, it is designed to withstand exposure to DEF and harsh operating conditions for long-lasting service life. Each unit is thoroughly tested for sensor accuracy, electrical functionality, and durability. Ideal for professional diesel technicians and fleet maintenance operations, this OEM DEF head unit supports efficient emissions management and dependable performance for Cummins ISL engines used in Terex equipment.
PEOPLE ALSO ASKS | BLOG(S)
The DEF (Diesel Exhaust Fluid) Head Unit with part number 37340 is a key component for machines using a Cummins ISL engine paired with Terex equipment. Mounted atop the DEF tank, this unit functions as the interface and control module for the DEF system — managing fluid status, delivery, and communication with the engine’s emissions control system.
What Its Role Includes
- Fluid Level Monitoring
- It detects how much DEF remains in the tank and conveys that information to the engine control module (ECM) so the system can signal if fluid is low.
- Temperature Sensing
- Built-in sensor tracks DEF fluid temperature. If the fluid is too cold or too warm, dosing might be affected and the system needs to know.
- Fluid Routing (Header Function)
- As a tank header, it provides the pickup path for drawing DEF from the tank into the dosing or injection system, and often includes a return path back into the tank for unused fluid.
- Filtration & Protection
- It typically houses an internal screen or filter that prevents crystals or particles from flowing out of the tank and into sensitive downstream components.
- Signal & Communication
- Sends data (level, temperature, etc.) to the ECM or emission controller so dosing decisions, diagnostics, and protection actions can be taken.
Even though the head unit might look like a simple tank cap, the OEM 37340 unit is critical for the SCR system to function properly. Without accurate sensing of DEF status, correct fluid routing, and clean fluid, the engine can face errors, system derates, or fail to stay compliant with emissions regulations.
The DEF (Diesel Exhaust Fluid) Head Unit is a crucial part of your vehicle’s emissions system. It measures the DEF level, temperature, and quality to ensure your truck remains compliant and efficient. When the unit fails, many drivers wonder — can it be serviced, or does it have to be replaced?
Can a DEF Head Unit Be Serviced?
The short answer is no — a DEF Head Unit is not serviceable. It’s a sealed electronic component that houses several sensitive sensors. Once these internal parts fail or become contaminated, they cannot be cleaned, recalibrated, or repaired without compromising the unit’s integrity.
Why It’s Not Serviceable:
- Sealed construction
- The unit is permanently sealed to protect internal electronics from DEF exposure.
- Complex sensors
- The level, temperature, and quality sensors are precision-calibrated and cannot be reset or serviced.
- Risk of contamination
- Opening the unit can introduce moisture or debris, leading to immediate failure.
What to Do When It Fails
If your DEF Head Unit starts to give inaccurate readings or triggers fault codes, replacement is the only reliable fix. Installing a new OEM-quality unit ensures proper communication with the engine control module (ECM) and restores emissions compliance.
How to Prevent Early Failure
- Use only certified, clean DEF fluid that meets ISO 22241 standards.
- Store DEF in sealed, temperature-controlled containers.
- Inspect the DEF system regularly for buildup, corrosion, or leaks.
- Avoid contamination by using dedicated DEF refilling tools.
A DEF Head Unit is not serviceable due to its sealed design and sensitive internal sensors. When it fails, replacement is the only safe and effective solution. Preventive maintenance and proper DEF handling are the best ways to maximize lifespan and avoid costly downtime.
Extreme temperature cycling, DEF contamination, moisture intrusion or mechanical vibration can all degrade sensor performance.
Typically no, but performing a diagnostic reset ensures the ECM recognizes the new sensor correctly.
Always use certified DEF, keep the tank sealed, and clean connectors during service inspections.
Yes — strong vibration or misalignment can damage the sensor body or internal electronics.
Cummins DEF Head Units
