
Cummins L9 SCR 2018-2021: OEM 5418521
CUMMINS L9 SCR 2018-2021: OEM 5418521

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Remanufactured Tamerx SCR, Tamerx part number 5418521RM-SCR ( OEM Part Number 5418521 ). 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 OEM | 5418521 |
| Additional OEM | 5418521 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490550773 |
| WEIGHT | 75.00 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.
Designed for 2018–2021 Cummins L9 engines, the Cummins L9 SCR (OEM 5418521) is an essential component of the diesel exhaust aftertreatment system. This Selective Catalytic Reduction (SCR) unit works with diesel exhaust fluid (DEF) to convert nitrogen oxides in the exhaust stream into less harmful gases before they exit the vehicle. Manufactured to meet original equipment specifications, it is engineered for proper fitment and dependable integration with the existing emissions system. The durable construction is intended to withstand the high temperatures and demanding operating conditions commonly found in heavy-duty diesel applications. Replacing a worn or restricted SCR unit with the OEM 5418521 helps maintain proper exhaust aftertreatment operation and supports compliance with emissions regulations.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2018 | Cummins | L9 | ||||
| 2019 | Cummins | L9 | ||||
| 2020 | Cummins | L9 | ||||
| 2021 | Cummins | L9 | ||||
PEOPLE ALSO ASKS | BLOG(S)
The Cummins L9 SCR (Selective Catalytic Reduction) system, OEM 5418521, is an important part of the emissions control system used in many Cummins L9 engines from 2018 to 2021. This component helps reduce nitrogen oxide (NOx) emissions by using diesel exhaust fluid (DEF) to convert harmful gases into less harmful compounds before the exhaust exits the vehicle. Proper care helps keep the SCR system functioning correctly and supports the overall reliability of the aftertreatment system.
Because the SCR operates in a high-temperature exhaust environment and depends on clean DEF and proper exhaust flow, routine maintenance is essential.
Tips for Maintaining Your Cummins L9 SCR System
- Use high-quality diesel exhaust fluid (DEF)
- Always use DEF that meets recommended standards to prevent contamination inside the SCR catalyst.
- Store DEF properly
- Keep DEF sealed and stored in clean containers to avoid dirt, moisture, or temperature damage.
- Inspect the DEF system regularly
- Check the DEF tank, pump, injector, and lines for leaks, buildup, or blockages.
- Monitor the exhaust system
- Look for exhaust leaks or damaged components that could affect SCR operation.
- Address warning lights and fault codes quickly
- Diagnosing emissions-related alerts early can help prevent additional strain on the SCR unit.
Why Regular Maintenance Matters
Taking care of the Cummins L9 SCR OEM 5418521 helps maintain effective emissions treatment and supports the operation of the entire aftertreatment system. Routine inspections, proper DEF handling, and timely diagnostics can help extend the service life of this essential emissions component.
If your Selective Catalytic Reduction (SCR) system is failing, it’s important to address the problem as soon as possible. The SCR system helps reduce nitrogen oxide emissions by injecting diesel exhaust fluid (DEF) into the exhaust stream. When the system is not working correctly, it can trigger warning lights, fault codes, or emissions-related alerts.
The first step is to confirm the issue with a diagnostic scan. Modern diesel vehicles monitor the emissions system closely, and a scan tool can identify trouble codes related to the SCR catalyst, sensors, or DEF components.
If the SCR system is failing, consider taking the following steps:
- Run a diagnostic scan
- to identify emissions-related trouble codes
- Check the DEF level and fluid quality
- to ensure it is not contaminated
- Inspect the DEF injector
- for blockages or dosing issues
- Examine sensors and wiring
- that monitor emissions levels
- Replace the SCR catalyst
- if it is contaminated or damaged
It’s also important to determine the root cause of the failure. Poor-quality DEF, faulty sensors, or issues within the engine can interfere with the SCR system’s operation.
Addressing the issue early can help restore proper emissions control and prevent further complications within the exhaust aftertreatment system.
The module is installed in the aftertreatment assembly along the vehicle’s exhaust system.
Medium-duty and heavy-duty commercial vehicles equipped with Cummins L9 engines may use this SCR component.
The module contains a catalytic substrate that promotes chemical reactions as exhaust gases flow through it.
The diesel oxidation catalyst and diesel particulate filter typically process exhaust gases before they reach the SCR catalyst.




















