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Pierce Cummins ISL DEF Head Unit

PIERCE 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 3350441
PART TYPE DEF Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE Cummins
ENGINE TYPE ISL
YEAR
PART NUMBER 4310-18-33
APPLICATION NOTES Pierce
ADDITIONAL NOTES DEF Header, 40 MICRON, 18"

PRODUCT DESCRIPTION

This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 4310-18-33 ( OEM Part Number 3350441 ). 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 OEM3350441
Additional OEM3136685, 3350441

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490541450
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.


Introducing the Pierce Cummins ISL DEF Head Unit — precision-engineered for your ISL-powered fire apparatus and heavy-duty rigs. This rugged module delivers real-time accuracy in monitoring DEF level, temperature, and quality, helping maintain SCR system integrity and prevent unwanted derates. Built for durability and seamless integration, it’s the emissions solution that keeps you ready for action when seconds count.

PEOPLE ALSO ASKS | BLOG(S)

Modern fire and rescue vehicles demand reliability under pressure—especially from their emissions systems. The SCR (Selective Catalytic Reduction) circuit depends on precise dosing and sensing, and the Pierce Cummins ISL DEF Head Unit (OEM 5142426-01) is right at the heart of that system. If this module fails or drifts, you could face warning codes, engine derates, or emissions violations—none of which you want in an emergency.

  • Monitors DEF fluid level, temperature, and urea concentration, feeding accurate data to the engine’s ECU

  • Controls precise dosing of DEF into the exhaust stream to enable NOx reduction in the SCR system

  • Built to OEM 5142426-01 tolerances to ensure plug-and-play compatibility with Pierce / Cummins ISL platforms

  • Helps prevent system faults, emissions warnings, and engine derates tied to incorrect or drifting sensor values

  • Engineered for durability in fire apparatus use: resilient to vibration, thermal cycles, and exposure to DEF chemistry

  • Designed for easier replacement to minimize apparatus downtime

When a DEF head fails, symptoms often show up as check engine lights or emissions warnings—sometimes in the worst possible moment. But by installing the correct OEM 5142426-01 Pierce Cummins ISL DEF Head Unit, you restore integrity to your emissions feedback loop, protect your SCR function, and reduce the risk of surprise system failures. In apparatus service, there’s no room for weak links—make sure this one is solid.

The DEF (Diesel Exhaust Fluid) head unit is a sensitive component designed to monitor fluid level, quality, and temperature. Because DEF is highly responsive to changes in climate, extreme temperatures can directly impact the accuracy and longevity of the DEF head unit. Understanding how temperature plays a role helps operators protect their systems and avoid costly downtime.

Ways Temperature Affects DEF Head Unit Performance

  • Freezing Conditions
    DEF begins to freeze at about 12°F (-11°C). When frozen, the sensors may give inaccurate readings until the fluid thaws.

  • High Heat Exposure
    Excessive heat can degrade DEF quality and put stress on the unit’s electronics, leading to false alerts or premature wear.

  • Rapid Temperature Changes
    Quick shifts between hot and cold can strain internal sensors, increasing the risk of malfunction.

  • Crystallization Risks
    Repeated freeze-thaw cycles may cause DEF to crystallize, creating buildup that interferes with sensor accuracy.

  • Outdoor Storage Challenges
    Vehicles stored outdoors in extreme climates are more likely to experience temperature-related DEF head unit problems.

Temperature has a major influence on the performance of a DEF head unit. By limiting exposure to extreme weather, using proper storage practices, and conducting regular inspections, operators can reduce temperature-related failures and extend the life of this essential emissions component.

Warning lights, DEF system error codes, or the engine going into reduced power mode are common signs.

The vehicle may display false DEF warnings or trigger engine derate to protect emissions.

Indirectly, yes—incorrect DEF dosing from bad readings can reduce engine efficiency.

It should be inspected during regular maintenance or when DEF system errors appear.

Cummins DEF Head Units

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