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CAT Caterpillar C4.4, C3.6 DEF Head Unit

CAT CATERPILLAR C4.4, C3.6 DEF HEAD UNIT

Shipping ICON

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY ICON

WARRANTY
1M MILES OR 1 YEAR

$585.00

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 5913427
PART TYPE DEF Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE Caterpillar
ENGINE TYPE C4.4, C3.6
YEAR
PART NUMBER 1795-11-1
APPLICATION NOTES CAT
ADDITIONAL NOTES DEF Header, 40 MICRON, 11"

PRODUCT DESCRIPTION

This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 1795-11-1 ( OEM Part Number 5913427 ). This part is primarily made for a Caterpillar C4.4, C3.6, 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 OEM5913427
Additional OEM5356922, 5913427

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490541313
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.


Step up your emissions game with the CAT Caterpillar C4.4 / C3.6 DEF Head Unit — engineered for precision, durability, and seamless integration. This rugged, OEM-grade unit tracks DEF fluid level, temperature, and quality in real time, helping your SCR system run lean, clean, and derate-free. Built to withstand harsh environments, it’s the smart emissions upgrade your Caterpillar engine deserves.

PEOPLE ALSO ASKS | BLOG(S)

When you’re operating equipment or trucks with CAT C4.4 or C3.6 engines, each link in the emissions aftertreatment system has to work flawlessly. One of the most important—but overlooked—components is the DEF (Diesel Exhaust Fluid) head unit. The correct DEF head ensures accurate sensing, precise dosing, and reliable communication between your DEF system and the engine control module. If it malfunctions or drifts out of spec, you’re looking at error codes, derates, or regulatory compliance risks.

  • Monitors DEF fluid level, temperature, and urea concentration, providing real-time data to your ECU

  • Regulates accurate dosing of DEF into the exhaust stream, enabling the SCR (Selective Catalytic Reduction) system to properly reduce NOx emissions

  • Built to match CAT’s OEM specifications for the C4.4 and C3.6 platforms for proper fit and calibration

  • Helps prevent emissions fault codes, warning lamps, or engine derates resulting from sensor errors

  • Designed to withstand harsh conditions—vibration, temperature swings, and exposure to DEF’s corrosive nature

  • Engineered for efficient replacement, allowing for quicker repairs and less downtime

Don’t let a compromised DEF head unit become the weak link in your emissions system. By installing an OEM-matched DEF Head for your CAT C4.4 or C3.6 engine, you restore system accuracy, protect against unexpected faults, and keep your machine running clean and compliant. This is one of those parts that might be small in size—but is huge in importance.

 

The DEaF (Diesel Exhaust Fluid) head unit is a crucial part of your vehicle’s emissions system. It monitors DEF level, temperature, and quality, sending vital information to the engine control module (ECM). When the unit begins to fail, inaccurate data or system errors can lead to warnings, reduced performance, and even costly downtime. Recognizing the signs early can help you take action before the problem escalates.

Common Signs of a Failing DEF Head Unit

  • Dashboard Warning Lights
    The check engine light or DEF system alerts often appear first when the head unit starts to malfunction.

  • Recurring Diagnostic Trouble Codes (DTCs)
    Fault codes such as P203F (DEF level), P205B (temperature sensor issue), or P207F (quality sensor issue) frequently point to DEF head problems.

  • Inaccurate DEF Readings
    The system may display the tank as empty when it’s not, or show full even when DEF levels are low.

  • False DEF Quality Alerts
    You might see poor-quality DEF warnings despite using fresh, certified fluid.

  • Reduced Engine Power or Derate Mode
    If the ECM cannot verify accurate DEF information, it may reduce speed or power to maintain compliance.

  • Crystallization or Build-Up
    DEF crystals forming around sensors can interfere with accuracy, causing erratic behavior or false alerts.

A failing DEF head unit can quickly shift from minor alerts to serious performance restrictions. By recognizing warning lights, recurring codes, or inaccurate readings early, you can prevent full derates and costly downtime. Timely maintenance and inspections are the key to keeping your DEF system reliable and compliant.

Use diagnostics to compare sensor readings (level, temperature) to expected values and check for fault codes.

Depressurize the system, disconnect electrical connections, and unbolt the head unit following safe procedures.

With proper maintenance and clean DEF fluid, it typically lasts several years in line with the SCR system.

Very low temps can slow or block flow; high temps may stress seals or electronics over time.

Caterpillar DEF Head Units

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