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MCNEILUS Cummins ISL DEF Head Unit

MCNEILUS CUMMINS ISL DEF HEAD UNIT

Shipping ICON

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY ICON

WARRANTY
1M MILES OR 1 YEAR

$895.00

CORE CHARGE:

$250.00
iCORE DISCLAIMER: The CORE charge is a 30 day hold and will not be processed as long as the CORE is returned within 30 days. If you do not have a CORE or fail to return the CORE within 30 days, the CORE charge hold amount will be processed at that time.

AVAILABILITY IN STOCK
OEM NUMBER 1604688
PART TYPE DEF Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE Cummins
ENGINE TYPE ISL
YEAR
PART NUMBER 4310-18-31
APPLICATION NOTES MCNEILUS
ADDITIONAL NOTES DEF Header, 40 MICRON, 18"

PRODUCT DESCRIPTION

This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 4310-18-31 ( OEM Part Number 1604688 ). 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 OEM1604688
Additional OEM1554670, 1604688

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490541436
WEIGHT8.00 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.


Keep your fleet’s emissions in check with the MCNEILUS Cummins ISL DEF Head Unit — precision-engineered to deliver real-time monitoring of DEF level, temperature, and quality. Rugged and reliable, this head unit integrates seamlessly with your SCR system and helps prevent derates, ensuring your Cummins ISL engine stays compliant and performing mile after mile.

PEOPLE ALSO ASKS | BLOG(S)

Modern clean emissions systems rely on precise sensing and fluid control—and no component is more critical to that mission than the DEF (Diesel Exhaust Fluid) head unit. For McNeilus trucks or vehicles running a Cummins ISL engine, the McNeilus DEF Head Unit (OEM 1604688, Tamerx part 4310-18-31) is mission-critical. If it falters, your SCR system, diagnostics, and even regulatory compliance are at risk.

  • Monitors DEF fluid parameters such as level, temperature, and urea concentration, providing accurate data to the engine control module

  • Regulates precise dosing of DEF into the exhaust stream so the SCR system can reduce NOx emissions effectively

  • Built to the OEM 1604688 specification, ensuring proper fit, calibration, and integration with McNeilus / Cummins ISL systems

  • Helps prevent fault codes, check engine warnings, and engine derates caused by misread or degraded sensor signals

  • Equipped with a 40-micron filter, guarding against contamination that degrades performance

  • Designed to withstand real-world stress: vibration, thermal cycling, and exposure to DEF’s corrosive chemistry

Emissions failures often start with a sensor losing accuracy—typically the DEF head. Installing the OEM 1604688 McNeilus Cummins ISL DEF Head Unit restores sensor integrity, keeps your aftertreatment system functioning smoothly, and helps avoid surprises in compliance or downtime. In the world of emission systems, this is one part you can’t afford to overlook.

 

The DEF (Diesel Exhaust Fluid) head unit is a vital component in modern diesel engines, responsible for monitoring DEF level, quality, and temperature. Like any part of the emissions system, it has a limited lifespan. Knowing how long a DEF head unit typically lasts can help operators plan maintenance and avoid unexpected downtime.

Factors That Affect DEF Head Unit Lifespan

  • Average Lifespan
    Under normal operating conditions, a DEF head unit generally lasts 5 to 7 years.

  • Vehicle Usage
    Heavy-duty trucks or high-mileage vehicles may experience shorter lifespans compared to light-use vehicles.

  • Environmental Conditions
    Exposure to extreme heat, freezing weather, or constant outdoor storage can accelerate wear and shorten service life.

  • DEF Fluid Quality
    Using certified, uncontaminated DEF fluid helps protect sensors and prolong the unit’s durability.

  • Maintenance Practices
    Routine inspections, tank cleaning, and careful handling during service extend the overall lifespan of the head unit.

  • Early Signs of Failure
    Frequent fault codes, false quality alerts, or inaccurate fluid readings often signal the head unit is nearing the end of its life.

While a DEF head unit is built to last several years, its actual service life depends heavily on how the vehicle is used and maintained. By using high-quality DEF, protecting the system from extreme conditions, and performing routine inspections, operators can maximize lifespan and reduce the risk of costly breakdowns.

It should be checked during periodic DEF or emissions system service and whenever warning codes appear.

se ISO-compliant DEF, avoid contamination, regularly inspect heater and sensors, and clean or replace the strainer.

Use diagnostic tools to compare sensor readings (level, temperature) to expected values and confirm that no fault codes are active.

The engine may enter derate mode, display DEF system warnings, or lose emissions compliance until the unit is restored.

Cummins DEF Head Units

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