
Cummins B6.7, L9 DOC Filter 2018-2021: OEM 4394859
CUMMINS B6.7, L9 DOC FILTER 2018-2021: OEM 4394859

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Remanufactured Tamerx DOC Filter, Tamerx part number 102-0154RM-DOC-8 ( OEM Part Number 4394859 ). 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 B6.7, L9, production years 2018-2021, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: Inlet Catalyst
OEM NUMBERS
| Primary OEM | 4394859 |
| Additional OEM | 4394859 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490549661 |
| WEIGHT | 35.00 LBS |
SHIPPING OPTIONS
Ship Weight : 35.00 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.
Built for 2018–2021 Cummins B6.7 and L9 engines, the OEM 4394859 DOC Filter is a vital component in maintaining proper exhaust aftertreatment function and emissions compliance. This Diesel Oxidation Catalyst (DOC) works to convert harmful exhaust gases into less harmful compounds before they continue through the DPF and SCR system. Designed to meet original equipment specifications, it provides precise fitment and seamless compatibility with factory-installed sensors and mounting hardware. Its rugged construction is engineered to withstand high exhaust temperatures and the daily demands of medium- and heavy-duty applications. As a direct OEM replacement, this Cummins B6.7 and L9 DOC Filter supports consistent system operation while helping reduce the risk of unexpected downtime. Tamerx Diesel Products LLC supplies dependable diesel aftertreatment components that align with strict manufacturer standards.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2018 | Cummins | B6.7 | L9 | |||
| 2019 | Cummins | B6.7 | L9 | |||
| 2020 | Cummins | B6.7 | L9 | |||
| 2021 | Cummins | B6.7 | L9 | |||
PEOPLE ALSO ASKS | BLOG(S)
Designed for medium- and heavy-duty applications, the Cummins B6.7, L9 DOC Filter 2018–2021 (OEM 4394859) is a Diesel Oxidation Catalyst (DOC) used within the engine’s aftertreatment system. This component is specifically built for Cummins B6.7 and L9 engines manufactured between 2018 and 2021.
The DOC is positioned at the front of the aftertreatment assembly, where it treats exhaust gases immediately after they exit the engine. Its primary purpose is to initiate oxidation reactions that convert harmful pollutants into less harmful compounds before the gases move downstream.
What OEM 4394859 Includes
- A honeycomb-style catalyst substrate
- A precious metal washcoat (typically platinum and/or palladium)
- A high-temperature stainless steel housing
- Integrated flanges for direct exhaust connection
- Sensor ports for monitoring exhaust conditions
As exhaust flows through the catalyst substrate, carbon monoxide and unburned hydrocarbons are chemically converted into carbon dioxide and water vapor. This process also generates heat that supports proper Diesel Particulate Filter (DPF) function.
In short, the OEM 4394859 DOC filter is a critical emissions control component that ensures 2018–2021 Cummins B6.7 and L9 engines operate within federal regulations while maintaining proper aftertreatment system function.
Caring for your DOC (Diesel Oxidation Catalyst) filter starts with protecting the engine systems that feed into it. Because the DOC processes exhaust gases directly, anything that affects combustion quality or introduces contaminants can shorten its lifespan.
Routine maintenance and smart driving habits are the foundation of long-term reliability.
To properly care for your DOC filter:
- Use high-quality diesel fuel to limit deposit buildup
- Follow recommended oil change intervals
- Use manufacturer-approved engine oil and fluids
- Repair leaking injectors promptly
- Fix oil or coolant leaks before they reach the exhaust system
- Respond quickly to check engine or emissions warning lights
Operating conditions also play an important role. Frequent short trips that prevent the engine from reaching full operating temperature can lead to soot accumulation. Allowing the engine to run long enough to reach normal exhaust temperatures helps maintain proper catalyst function.
Regular inspections of exhaust components, sensors, and related systems can catch small issues early. Addressing concerns before they escalate helps prevent costly repairs and unexpected downtime.
With consistent maintenance and timely repairs, your DOC filter can continue functioning as intended and support reliable vehicle operation.
Part 4394859 is a diesel oxidation catalyst designed for emission regulation within the exhaust system.
It provides a controlled passage where oxidation reactions occur to condition exhaust before further treatment.
Yes, it works in conjunction with components like the DPF and SCR to manage exhaust emissions effectively.
Aftertreatment system warnings or exhaust flow irregularities can suggest the DOC filter needs inspection.













