
Cummins B6.7 DOC Filter 2018-2021: OEM 4394940
CUMMINS B6.7 DOC FILTER 2018-2021: OEM 4394940

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 102-0184RM-DOC-3 ( OEM Part Number 4394940 ). 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, 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 | 4394940 |
| Additional OEM | 4394940 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490549791 |
| 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.
Supporting 2018–2021 Cummins B6.7 engine applications, the OEM 4394940 DOC Filter is designed to maintain proper exhaust aftertreatment function and ensure emissions compliance. This Diesel Oxidation Catalyst (DOC) converts harmful exhaust gases into less harmful compounds before they continue through the downstream DPF and SCR system. Manufactured to original equipment specifications, it delivers precise fitment and dependable compatibility with factory-installed sensors and mounting hardware. Its durable construction is engineered to withstand high exhaust temperatures and the demanding conditions of commercial vehicle operation. As a direct OEM replacement, this Cummins B6.7 DOC Filter helps preserve the reliability of the aftertreatment system while reducing the risk of unexpected downtime. Tamerx Diesel Products LLC provides dependable diesel emissions components that align with strict manufacturer standards.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2018 | Cummins | B6.7 | ||||
| 2019 | Cummins | B6.7 | ||||
| 2020 | Cummins | B6.7 | ||||
| 2021 | Cummins | B6.7 | ||||
PEOPLE ALSO ASKS | BLOG(S)
The Cummins B6.7 DOC Filter 2018–2021 (OEM 4394940) is built with several specialized components that allow it to function effectively within the engine’s aftertreatment system. As a Diesel Oxidation Catalyst (DOC), its structure is designed to handle high exhaust temperatures while enabling chemical reactions that reduce harmful emissions.
At the center of the assembly is the catalyst core, which is protected by a durable outer housing and supported by additional structural elements that ensure proper fitment within the exhaust system.
Main Components of OEM 4394940
- Catalyst substrate
- A ceramic or metallic honeycomb structure that provides a large surface area for exhaust gases to pass through.
- Precious metal washcoat
- Typically platinum and/or palladium applied to the substrate to initiate oxidation reactions.
- Stainless steel outer housing
- A high-temperature resistant shell that protects the internal catalyst components.
- Mounting flanges
- Connection points that secure the DOC into the exhaust assembly.
- Insulation or support matting
- Material that stabilizes the catalyst substrate and manages thermal expansion.
- Sensor ports
- Openings that allow temperature or oxygen sensors to monitor exhaust conditions.
Each of these components works together to ensure proper exhaust treatment. In Cummins B6.7 engines from the 2018–2021 model years, the OEM 4394940 DOC filter plays a critical role in maintaining emissions compliance and supporting the operation of downstream aftertreatment components.
Maintaining the lifespan of your DOC (Diesel Oxidation Catalyst) filter starts with keeping your engine and exhaust system in good condition. Because the DOC processes exhaust gases, any contamination or combustion imbalance can shorten its service life.
Preventative maintenance and attentive driving habits can help reduce buildup and protect the catalyst material inside the filter.
To help prolong the lifespan of your DOC filter:
- Use high-quality diesel fuel to minimize residue and deposits
- Follow manufacturer-recommended oil change intervals
- Use approved engine oil and fluids
- Repair faulty fuel injectors as soon as possible
- Fix oil or coolant leaks before they contaminate the exhaust
- Avoid excessive idling whenever possible
- Address check engine or emissions warning lights promptly
Driving conditions also make a difference. Frequent short trips that prevent the engine from reaching normal operating temperature can contribute to soot accumulation. Allowing the vehicle to reach proper exhaust temperatures helps keep the catalyst functioning properly.
Routine inspections of sensors, exhaust connections, and related components can catch issues early. By staying proactive with maintenance and repairs, you can reduce the likelihood of premature DOC filter failure and avoid unnecessary downtime.
Catalytic materials inside the filter promote oxidation reactions that convert hydrocarbons and carbon monoxide.
Replacement may be necessary when the filter becomes restricted or no longer effectively processes exhaust gases.
Matching the part number on the existing catalyst module with 4394940 confirms compatibility.
Yes, it functions with other aftertreatment parts such as the diesel particulate filter and SCR system.









