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Cummins L9 SCR 2018-2021: OEM 4394720

CUMMINS L9 SCR 2018-2021: OEM 4394720

Shipping ICON

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY ICON

WARRANTY
1M MILES OR 1 YEAR

$4,995.00

AVAILABILITY IN STOCK
OEM NUMBER4394720
PART TYPESCR
BRANDTamerx Diesel Products
ENGINE MAKECummins
ENGINE TYPEL9
YEAR2018-2021
PART NUMBER4394720RM-SCR
APPLICATION NOTESNavistar, 250-320, EPA17

PRODUCT DESCRIPTION

This is a Remanufactured Tamerx SCR, Tamerx part number 4394720RM-SCR ( OEM Part Number 4394720 ). All parts are proudly remanufactured in the U.S.A. to the highest of OEM standards, and improvements are often applied to the original design in the remanufacturing process. This part is primarily made for a Cummins L9, production years 2018-2021, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here

OEM NUMBERS

Primary OEM4394720
Additional OEM4394720

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490551947
WEIGHT75.00 LBS

SHIPPING OPTIONS

Ship Weight : 75.00 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.


Hit the road with confidence and cleaner emissions using the Cummins L9 SCR 2018–2021: OEM 4394720, engineered to reduce harmful NOx output while helping your engine run efficiently. This genuine SCR module meets strict OEM standards for a precise fit and long-lasting durability across L9 applications. Built to handle demanding duty cycles, it supports smoother performance and regulatory compliance. Choose a solution that keeps your truck running cleaner and stronger, mile after mile.

FITMENT CHART

YEARMAKEENGINE(S)
2018Cummins L9
2019Cummins L9
2020Cummins L9
2021Cummins L9

PEOPLE ALSO ASKS | BLOG(S)

Maintaining a reliable emission aftertreatment system is a priority for truck owners who want to stay compliant with environmental standards and avoid unexpected service issues. The Cummins L9 SCR 2018–2021: OEM 4394720 is a core part of the Selective Catalytic Reduction (SCR) system that helps reduce harmful nitrogen oxides (NOx) in diesel exhaust. Knowing what makes this SCR unit important and when to consider inspection or replacement can help you protect your emission system and keep your truck running cleanly.

  • Specifically engineered for Cummins L9 engines from 2018 through 2021, the OEM 4394720 SCR unit fits directly into the emission aftertreatment system for precise compatibility.

  • The SCR (Selective Catalytic Reduction) process injects diesel exhaust fluid (DEF) into the exhaust stream, where a chemical reaction converts NOx into harmless nitrogen and water vapor.

  • A well-functioning SCR unit supports accurate DEF dosing, which is essential for proper NOx reduction and helps minimize unnecessary DEF consumption.

  • Early signs of SCR issues can include emission-related warning lights, unexpected DEF depletion, or diagnostic trouble codes tied to the aftertreatment system.

  • Routine inspection and maintenance of the SCR unit can help catch potential problems before they lead to service interruptions or engine derates.

  • Choosing the genuine OEM 4394720 SCR ensures proper fitment and function, reducing the risk of emission faults caused by incorrect or inferior parts.

  • Built to Cummins’ original specifications, this SCR module is designed to withstand the heat, vibration, and long-haul conditions typical of everyday trucking.

  • Installing the correct SCR component during scheduled maintenance helps maintain emission compliance and supports overall emission system longevity.

Selecting the Cummins L9 SCR 2018–2021: OEM 4394720 from Tamerx Diesel Parts means equipping your emission control system with a quality, engine-specific component. Timely inspection and replacement when needed help ensure your truck stays emission-compliant, dependable, and ready for the road ahead.

The Selective Catalytic Reduction (SCR) system is designed to provide long-term emissions control in modern diesel engines. Built to handle high exhaust temperatures and continuous operation, the SCR catalyst can last many miles under normal conditions. However, several factors can influence how long the system performs effectively before requiring replacement.

  • DEF quality plays a major role in SCR lifespan. Contaminated or incorrect Diesel Exhaust Fluid can damage the catalyst and reduce efficiency.

  • Excessive oil consumption can allow oil to enter the exhaust stream, coating the catalyst and shortening its service life.

  • Coolant leaks inside the engine may introduce harmful deposits that permanently damage the SCR internally.

  • Unresolved Diesel Particulate Filter (DPF) issues can cause improper exhaust flow or excessive heat, placing added stress on the SCR.

  • Frequent short trips or excessive idling may prevent the exhaust system from reaching optimal operating temperatures.

  • Faulty sensors or improper DEF dosing can lead to long-term strain on the system if not corrected promptly.

  • Operating conditions such as heavy loads or severe-duty use can gradually impact aftertreatment components over time.

The lifespan of an SCR system largely depends on proper maintenance and overall engine health. Using clean DEF, addressing engine problems quickly, and keeping the entire aftertreatment system in good condition can help extend SCR durability and maintain reliable emissions control.

Using clean DEF, inspecting sensors, and addressing warning codes promptly help maintain system efficiency. Preventive attention reduces the likelihood of larger aftertreatment issues.

Faulty wiring or poor connections can interfere with sensor communication and DEF injection control. Electrical irregularities may mimic catalyst performance problems.

Reliable SCR performance helps maintain regulatory compliance and stable engine operation. Over time, this reduces unexpected downtime related to emissions faults.

The SCR works in coordination with other emissions components to manage exhaust gases efficiently. Balanced interaction ensures consistent pollutant reduction across varying conditions.

Cummins SCRs