
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-10 ( 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 | 00840490549685 |
| 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.
Manufactured for 2018–2021 Cummins B6.7 and L9 engines, the OEM 4394859 DOC Filter is designed to support proper exhaust aftertreatment function and maintain emissions compliance. This Diesel Oxidation Catalyst (DOC) helps convert harmful exhaust gases into less harmful compounds before they continue through the DPF and SCR assemblies. Built to original equipment specifications, it ensures precise fitment and dependable integration with factory-installed sensors and hardware. Its durable construction is engineered to handle high exhaust temperatures and the rigorous demands of commercial truck operation. Serving as a direct OEM replacement, this Cummins B6.7 and L9 DOC Filter helps preserve aftertreatment system reliability while reducing the risk of unnecessary downtime. Tamerx Diesel Products LLC supplies quality diesel emissions components that meet 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)
At the front of the aftertreatment system, the Cummins B6.7, L9 DOC Filter 2018–2021 (OEM 4394859) serves a critical emissions control function. As a Diesel Oxidation Catalyst (DOC), its main role is to treat exhaust gases immediately after they leave the engine.
The DOC initiates oxidation reactions that convert harmful pollutants into less harmful compounds before the exhaust reaches the Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) system. By addressing emissions at the first stage, it allows the rest of the system to operate correctly.
Primary Role of OEM 4394859
- Converts carbon monoxide into carbon dioxide
- Breaks down unburned hydrocarbons
- Generates heat to assist DPF regeneration
- Prepares exhaust gases for downstream treatment
- Supports EPA emissions compliance
Because the DOC is the first active treatment component, its condition directly affects the entire aftertreatment assembly. A restricted or damaged unit can disrupt exhaust flow and lead to system faults.
For 2018–2021 Cummins B6.7 and L9 engines, the OEM 4394859 DOC filter ensures proper integration with factory calibrations while maintaining consistent emissions control and system reliability.
The primary cause of DOC (Diesel Oxidation Catalyst) filter failure is contamination inside the exhaust system. When soot, oil, coolant, or unburned fuel enter the DOC, they coat the catalyst surface and reduce its ability to treat exhaust gases effectively. Over time, this buildup restricts flow and can lead to permanent damage.
Most contamination issues stem from underlying engine problems. If these concerns are not addressed quickly, the DOC filter can become clogged or overheated.
Common causes of DOC filter failure include:
- Excessive soot from incomplete combustion
- Faulty fuel injectors creating unburned fuel deposits
- Oil entering the exhaust from worn engine components
- Coolant leaks contaminating the catalyst
- Poor fuel quality leaving heavy residue
- Prolonged idling that prevents proper exhaust temperatures
Thermal stress is another contributing factor. Extreme temperature fluctuations can crack or melt the internal catalyst material, especially when excess fuel ignites in the exhaust system.
Ignoring warning lights or delaying routine maintenance often allows minor issues to escalate. Identifying engine concerns early and following recommended service intervals are key steps in preventing DOC filter failure and avoiding costly repairs.
You can confirm the requirement by matching part number 4394859 with the DOC filter specified on your current unit.
Yes, it integrates with components like the DPF and SCR to collectively manage emissions.
Aftertreatment warnings or indications of restricted exhaust flow can signal an issue with the DOC filter.
Yes, installation should include verifying correct alignment and torque to ensure proper sealing and fit.










