Cummins QSB, 3.8L Decomposition Reactor Tube 2015-2022: OEM 4377370
CUMMINS QSB, 3.8L DECOMPOSITION REACTOR TUBE 2015-2022: OEM 4377370
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Genuine New, Cummins Decomposition Reactor Tube, Cummins part number 4377370-OE ( OEM Part Number 4377370 ).This part is primarily made for a Cummins QSB, 3.8L, production years 2015-2022, and comes with a One Million Miles or One Year Warranty.
OEM NUMBERS
| Primary OEM | 4377370 |
| Additional OEM | 4377370 |
ADDITIONAL DETAILS
| CONDITION | Genuine New |
| UPC / Barcode | 00840490558496 |
| WEIGHT | 2.00 LBS |
SHIPPING OPTIONS
Ship Weight : 2.00 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 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, 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 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 to support proper diesel exhaust fluid distribution within the aftertreatment system, the Cummins QSB 3.8L Decomposition Reactor Tube (2015–2022) OEM 4377370 plays an important role in maintaining efficient exhaust treatment. Manufactured according to original equipment specifications, this reactor tube is designed for proper fitment with applicable Cummins QSB 3.8L engines within the specified model years. It helps facilitate the mixing and decomposition of diesel exhaust fluid (DEF) within the exhaust stream, preparing the necessary compounds for the selective catalytic reduction process that reduces nitrogen oxide (NOx) emissions. Its durable construction is designed to withstand elevated exhaust temperatures, vibration, and demanding operating conditions commonly encountered in industrial diesel equipment. Suitable for equipment owners, maintenance technicians, and professional diesel repair facilities, this OEM decomposition reactor tube provides a dependable replacement solution for maintaining proper DEF distribution and reliable long-term aftertreatment system operation.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2015 | Cummins | QSB | 3.8L | |||
| 2016 | Cummins | QSB | 3.8L | |||
| 2017 | Cummins | QSB | 3.8L | |||
| 2018 | Cummins | QSB | 3.8L | |||
| 2019 | Cummins | QSB | 3.8L | |||
| 2020 | Cummins | QSB | 3.8L | |||
| 2021 | Cummins | QSB | 3.8L | |||
| 2022 | Cummins | QSB | 3.8L | |||
PEOPLE ALSO ASKS | BLOG(S)
The main function of the Cummins QSB, 3.8L Decomposition Reactor Tube 2015-2022: OEM 4377370 is to support the decomposition and mixing of Diesel Exhaust Fluid (DEF) with hot exhaust gases before they enter the Selective Catalytic Reduction (SCR) system. This process helps convert DEF into ammonia, which is necessary for reducing harmful nitrogen oxide (NOx) emissions.
The decomposition reactor tube plays an important role in preparing the DEF and exhaust mixture for effective chemical reactions inside the SCR catalyst.
What Does the Decomposition Reactor Tube Do?
- Supports DEF decomposition The tube provides a pathway where injected DEF can break down under suitable exhaust temperature conditions, helping produce ammonia for the SCR process.
- Promotes proper DEF mixing It helps the injected DEF mix with hot exhaust gases before the mixture reaches the SCR catalyst.
- Supports NOx reduction The ammonia produced from DEF reacts with nitrogen oxides inside the SCR catalyst, converting them primarily into nitrogen and water vapor.
- Helps prevent DEF deposits Proper exhaust temperatures and DEF mixing help reduce the likelihood of crystallized deposits forming inside the decomposition tube.
- Maintains the intended exhaust pathway The tube directs exhaust gases and the DEF mixture toward downstream SCR components for further emissions treatment.
- Works with the DEF dosing system It operates alongside the DEF injector and related components to support proper distribution of DEF within the exhaust stream.
- Supports emissions compliance Effective DEF decomposition and mixing help the SCR system meet the emissions-control requirements of compatible Cummins QSB and 3.8L applications.
Important for Proper DEF Preparation
The Cummins QSB, 3.8L Decomposition Reactor Tube (OEM 4377370) plays an essential role in preparing the exhaust mixture for effective SCR treatment. If the tube becomes clogged, damaged, restricted, or affected by excessive DEF deposits, it may contribute to improper DEF mixing, SCR efficiency faults, emissions warning lights, or operating restrictions.
Using specification-correct DEF, maintaining the DEF dosing system, and addressing exhaust temperature or emissions-related problems promptly can help protect the decomposition reactor tube and support reliable aftertreatment operation.
Driving with a failing Decomposition Reactor Tube is generally not recommended, especially when the problem involves DEF crystallization, exhaust leaks, excessive heat, or recurring aftertreatment faults. Although the vehicle may continue operating, ignoring the issue can lead to additional SCR system problems and unexpected operating restrictions.
Here are several risks of driving with a failing Decomposition Reactor Tube:
- Excessive DEF crystallization A damaged or restricted tube can contribute to DEF deposit accumulation, interfering with proper DEF mixing and exhaust flow.
- Reduced SCR system efficiency Improper DEF distribution can affect ammonia formation and prevent the SCR catalyst from reducing NOx emissions effectively.
- Engine derate Persistent aftertreatment faults may cause the engine control system to restrict vehicle speed or engine output.
- Recurring emissions warning lights Problems involving DEF delivery or exhaust treatment may trigger check engine lights and SCR system warnings.
- Increased exhaust backpressure Severe deposits or internal restrictions can interfere with exhaust flow and affect normal engine operation.
- Abnormal exhaust temperatures Restrictions or related aftertreatment problems may contribute to unusual exhaust temperature conditions.
- Additional SCR component problems Continued operation with improper DEF mixing, contamination, or exhaust restrictions can affect downstream catalyst components.
- Exhaust leakage Cracks, damaged connections, or deteriorated seals may allow hot exhaust gases to escape, creating safety concerns.
- Unexpected vehicle downtime A worsening decomposition tube problem may eventually trigger operating restrictions or require immediate repairs.
If the vehicle is operating normally without critical warnings, a short trip to a repair facility may be possible, depending on the manufacturer's recommendations. However, severe derate, excessive exhaust heat, significant restrictions, or visible exhaust leaks should be addressed immediately.
Before replacing the Decomposition Reactor Tube, have the DEF injector, dosing system, exhaust connections, temperature sensors, and related SCR components inspected. Identifying the underlying cause can help prevent recurring deposits, unnecessary replacement, and further aftertreatment damage.
Yes, excessive deposits or internal obstructions can restrict exhaust flow through the 4377370 and interfere with normal aftertreatment operation.
Cleaning may be possible when permitted by Cummins service procedures, but a cracked, severely corroded, or structurally damaged 4377370 may require replacement.
Damaged mounting connections, loose hardware, or improper alignment can create exhaust leaks and place unnecessary mechanical stress on the tube.
The DEF dosing injector, exhaust connections, mounting hardware, sealing surfaces, and adjoining aftertreatment components should be inspected before installation.
Cummins Decomposition Reactor Tubes
