Nova Cummins ISB 6.7L DEF Head Unit
NOVA CUMMINS ISB 6.7L DEF HEAD UNIT
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 4310-18-13 ( OEM Part Number A179720 ).This part is primarily made for a Cummins ISB 6.7L, production years 2018-2024, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: DEF Header, 40 MICRON, 18"
OEM NUMBERS
| Primary OEM | A179720 |
| Additional OEM | A179720 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490540477 |
| WEIGHT | 8.00 LBS |
SHIPPING OPTIONS
Ship Weight : 8.00 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 precision and reliability, the Nova Cummins ISB 6.7L DEF Head Unit, OEM part number A179720, ensures accurate monitoring and control of diesel exhaust fluid (DEF) levels and temperature within the emissions system. Manufactured to meet OEM specifications, this DEF head unit provides exact fitment and dependable performance in demanding diesel applications. Built from high-quality, corrosion-resistant materials, it withstands exposure to DEF and extreme environmental conditions. Each unit is rigorously tested for sensor accuracy, electrical integrity, and long-term reliability. Ideal for professional diesel technicians and fleet maintenance operations, this OEM DEF head unit supports efficient emissions management and dependable operation for Cummins ISB 6.7L engines.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2018 | Cummins | ISB 6.7L | ||||
| 2019 | Cummins | ISB 6.7L | ||||
| 2020 | Cummins | ISB 6.7L | ||||
| 2021 | Cummins | ISB 6.7L | ||||
| 2022 | Cummins | ISB 6.7L | ||||
| 2023 | Cummins | ISB 6.7L | ||||
| 2024 | Cummins | ISB 6.7L | ||||
PEOPLE ALSO ASKS | BLOG(S)
The DEF (Diesel Exhaust Fluid) Head Unit with part number A179720 is a key component in vehicles using a Cummins ISB 6.7L engine outfitted with Nova build-or-equivalent applications. Mounted on the DEF tank, this unit integrates fluid monitoring, routing and communication functions to support the vehicle’s SCR (Selective Catalytic Reduction) emission system.
What It’s Used For
- Fluid Level Monitoring
- It senses how much DEF remains in the tank and communicates with the engine’s control system to alert when levels are low.
- Temperature Sensing
- It tracks DEF temperature to detect freezing or overheating conditions that might degrade performance or fluid quality.
- Fluid Routing / Header Function
- Acts as the header or interface for the DEF tank: providing a pickup path to the dosing/injection system and often a return path for excess fluid.
- Filtration & Protection
- Includes an internal filter or strainer to remove particles or crystals, protecting the downstream DEF injection components.
- Signal Communication
- Transmits sensor data (level, temperature, etc.) to the engine control module (ECM), allowing the system to accurately dose DEF, detect faults, and ensure emission compliance.
Although the head unit may appear as a tank-mounted cap or module, it performs the critical job of “knowing” the DEF status, maintaining the fluid’s condition, ensuring clean delivery, and providing the feedback the engine needs to meet emissions standards while running reliably.
The DEF (Diesel Exhaust Fluid) Head Unit is one of the most important components in your vehicle’s emissions system. It measures the DEF level, temperature, and quality, ensuring your truck remains compliant with emissions regulations. When it fails, your vehicle may enter derate mode, limiting power and performance. Understanding what causes a DEF Head Unit to fail can help you prevent costly downtime and repairs.
Common Causes of DEF Head Unit Failure
- DEF Contamination
- The number one cause of DEF Head Unit failure is contaminated DEF fluid. Dirt, dust, or other debris introduced during refills can clog sensors or corrode the internal components of the head unit. Even small amounts of fuel, oil, or coolant contamination can permanently damage sensitive sensors.
- Crystallization
- When DEF is exposed to air or temperature extremes, it can crystallize. These crystals form inside the DEF tank and on sensor surfaces, causing inaccurate readings or complete sensor failure over time.
- Extreme Temperatures
- The DEF Head Unit operates in a harsh environment. Freezing temperatures can cause fluid expansion that damages internal parts, while high heat accelerates sensor degradation and electronic failure.
- Poor Handling or Storage
- Using improper containers or tools during refills introduces debris into the system. DEF should always be stored in sealed, dedicated containers and kept away from direct sunlight to prevent chemical breakdown.
- Moisture and Corrosion
- Exposure to moisture or humidity can cause corrosion on the electrical connectors or internal components of the Head Unit, leading to intermittent faults or total failure.
- Normal Wear Over Time
- Even with proper care, DEF Head Units have a typical lifespan of 5 to 7 years. Continuous exposure to DEF fluid, vibration, and heat will eventually wear out the sensors and electronics.
How to Prevent DEF Head Unit Failure
- Always use certified, high-quality DEF fluid (meeting ISO 22241 standards).
- Store DEF in clean, sealed containers away from heat or freezing conditions.
- Avoid using fuel or oil funnels for DEF refills.
- Perform regular inspections for crystallization or corrosion.
- Address fault codes or warnings promptly to prevent additional damage.
Most DEF Head Unit failures are caused by contamination, crystallization, or environmental stress. By maintaining clean DEF handling practices and performing regular inspections, you can extend your unit’s lifespan and avoid unexpected downtime.
You may see warning lights, “Poor DEF Quality” messages, derate conditions, or inaccurate DEF level readings.
It sends electrical signals through CAN bus communication to report fluid level, quality, and temperature data.
Yes — the ECM may limit engine output to prevent emissions violations if incorrect DEF data is detected.
Check electrical connectors for corrosion, inspect wiring harness integrity, and confirm proper DEF quality and fluid level.
Cummins DEF Head Units
