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Perkins Engines Perkins DEF Head Unit

PERKINS ENGINES PERKINS 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 T434825
PART TYPE DEF Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE Perkins
ENGINE TYPE
YEAR
PART NUMBER 1731-18-2
APPLICATION NOTES Perkins Engines
ADDITIONAL NOTES DEF Header, Coaxial Heater, 40 MICRON, 18"

PRODUCT DESCRIPTION

This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 1731-18-2 ( OEM Part Number T434825 ). This part is primarily made for a Perkins , and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here

Additional Notes: DEF Header, Coaxial Heater, 40 MICRON, 18"

OEM NUMBERS

Primary OEMT434825
Additional OEMT400737, T434825

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490541290
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 Perkins Engines DEF Head Unit — precision-engineered to monitor DEF level, temperature, and quality in real time. Built to OEM standards and rugged enough for harsh environments, this unit integrates seamlessly into your SCR system to prevent derates, ensure compliance, and keep your engine running clean and confident mile after mile.

PEOPLE ALSO ASKS | BLOG(S)

In modern diesel engines, emission compliance hinges on accurate monitoring—and the DEF (Diesel Exhaust Fluid) head unit is one of the most critical sensors in that chain. The Perkins DEF Head Unit (OEM T434814) handles functions that many operators take for granted: sensing fluid level, temperature, and quality, then regulating dosing based on that data. When it fails or deviates from spec, error codes, derates, and extended downtime can follow.

  • Tracks DEF fluid level, temperature, and urea concentration, sending real-time readings to the ECU

  • Regulates the injection or dosing of DEF into the exhaust to support the SCR (Selective Catalytic Reduction) system in reducing NOx

  • Designed to meet OEM T434814 tolerances, ensuring your emissions system stays correctly calibrated

  • Helps prevent emission faults, warning lights, and engine derates caused by sensor drift or failure

  • Built to survive challenging conditions—vibration, temperature fluctuations, and exposure to DEF’s chemistry

  • Field-friendly for replacement, helping you restore functionality without lengthy downtime

Because the DEF head unit acts as a gatekeeper for your emissions system, it often reveals problems before anything else does. Replacing a faulty or aging unit with the OEM T434814 Perkins DEF Head restores sensor integrity, prevents unpredictable faults, and helps maintain compliance. In the world of aftertreatment, this is one component you don’t want to neglect.

The DEF (Diesel Exhaust Fluid) head unit is a vital component of a diesel engine’s emissions system, responsible for monitoring fluid level, temperature, and quality. When it fails, operators can face fault codes, reduced performance, or even engine derates. Fortunately, with proper maintenance, the lifespan of a DEF head unit can be significantly extended.

Key Maintenance Steps for DEF Head Units

  • Use High-Quality DEF Fluid
    Always use ISO 22241-certified DEF to avoid contamination that can damage sensitive sensors.

  • Inspect and Clean the DEF Tank
    Regularly check for dirt, debris, or crystallization buildup around the tank and sensors to ensure accurate readings.

  • Check Electrical Connections
    Inspect wiring and connectors for corrosion, looseness, or damage that may disrupt communication with the ECM.

  • Protect Against Extreme Temperatures
    Store vehicles and DEF fluid in conditions that minimize exposure to freezing or overheating, both of which stress sensors.

  • Add DEF System Checks to Routine Maintenance
    Include the head unit in scheduled service intervals to catch early signs of malfunction.

  • Handle with Care During Servicing
    Use proper tools and avoid rough handling when working around the DEF tank and head unit.

Consistent maintenance is the best way to extend the life of a DEF head unit. By using clean, certified fluid, protecting the system from extreme conditions, and inspecting it regularly, operators can prevent premature failures, reduce downtime, and keep their emissions systems running smoothly.

Excessive vibration or impact can damage sensors, connectors, or cause leaks and internal damage.

Possible codes include level sensor out of range, temperature sensor fault, filter/clog warning, heater circuit fault, or communication error.

Using clean, ISO-compliant DEF, avoiding contamination, verifying heater and sensor operations, and following proper inspection/cleaning schedules.

The system may issue warnings, the engine may go into reduced power or derate mode, and emissions control may be compromised until repaired.

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