REV Fire Group Cummins ISL DEF Head Unit
REV FIRE GROUP CUMMINS ISL 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 4310-18-12 ( OEM Part Number 1112302-002 ). This part is primarily made for a Cummins ISL, 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 | 1112302-002 |
| Additional OEM | 1009212-003, 1112302-002 |
ADDITIONAL DETAILS
| CONDITION | Remanufactured |
| UPC / Barcode | 00840490540460 |
| 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.
Built for precision and dependability, the REV Fire Group Cummins ISL DEF Head Unit OEM 1112302-002 is designed to ensure accurate Diesel Exhaust Fluid system operation in emergency vehicles powered by Cummins ISL engines. This genuine OEM component is manufactured to Cummins and REV Fire Group specifications, providing exact fitment, consistent DEF flow, and reliable system monitoring. By maintaining proper DEF function, it helps support emissions compliance and dependable engine performance under demanding conditions. Its rugged construction is built to handle the high-intensity environment of emergency service vehicles, offering long-lasting reliability and minimal downtime. For fire departments and fleet technicians, this DEF head unit delivers OEM-certified quality and trusted performance when reliability matters most.
PEOPLE ALSO ASKS | BLOG(S)
The DEF (Diesel Exhaust Fluid) Head Unit with OEM number 1112302-002 is a critical module installed on REV Fire Group vehicles using Cummins ISL engines. This unit is mounted on or in the DEF tank and acts as the interface between the fluid and the engine’s emission control system. Its purpose is to monitor, protect, and manage the DEF supply so the Selective Catalytic Reduction (SCR) system can reduce harmful emissions efficiently.
Key Uses & Functions
- Fluid Level Monitoring
- The head unit senses how much DEF remains in the tank and sends that information to the engine control module (ECM). This ensures that the system can alert the driver or operator when levels get low.
- Temperature Sensing
- It tracks the temperature of the DEF fluid. If the fluid is too cold (risk of freezing) or too warm for accurate dosing, the system can take protective actions.
- Fluid Routing / Header Function
- The head unit provides the pathway (pickup port) for drawing DEF into the dosing/injection system. It may also allow return flow (unused fluid back to the tank) to maintain balance.
- Filtering & Protection
- Before fluid leaves the head unit, it typically passes through an internal filter or strainer to remove particulate matter, debris, or crystals that could damage downstream components.
- Signal Communication
- It relays sensor data (level, temperature, condition) to the ECM or DEF controller, enabling accurate DEF dosing, diagnostics, and fault response.
OEM 1112302-002 is the control and sensing hub of the DEF system on REV Fire Group / Cummins ISL vehicles. It ensures the engine knows the fluid status, can dose it correctly, and protects the SCR system from errors or contamination.
The DEF (Diesel Exhaust Fluid) Head Unit is a crucial part of your truck’s emissions system. It monitors DEF level, temperature, and quality to keep your vehicle compliant with environmental standards. Like any component exposed to heat, fluid, and vibration, it has a limited service life — but proper care can help it last for years.
Average Lifespan of a DEF Head Unit
Under normal operating conditions, a DEF Head Unit typically lasts 5 to 7 years. Some units may last longer when the DEF system is properly maintained, while others can fail early if exposed to contamination or extreme conditions.
Factors That Affect Lifespan:
- DEF Quality
- Using low-quality or contaminated DEF introduces impurities that damage sensors.
- Storage Conditions
- Heat and freezing temperatures cause crystallization and sensor degradation.
- Handling Practices
- Using unclean containers during refills introduces debris into the DEF tank.
- Vehicle Use
- Heavy-duty applications and long idle periods put extra strain on the DEF system.
- Maintenance Routine
- Regular system inspections help catch early issues before they lead to failure.
How to Extend the Life of Your DEF Head Unit
You can help your DEF Head Unit reach — and even exceed — its expected lifespan by following these best practices:
- Always use certified, uncontaminated DEF fluid.
- Store DEF in sealed, temperature-controlled containers.
- Inspect the DEF tank for buildup or crystallization during maintenance.
- Address fault codes or warning lights immediately to prevent secondary damage.
Most DEF Head Units last 5 to 7 years, depending on maintenance and operating conditions. With clean DEF, proper handling, and routine system care, your Head Unit can deliver reliable performance and help avoid costly downtime or emissions-related issues.
No, it is a sealed electronic component and must be replaced if defective.
With clean DEF and regular maintenance, it can last several years under normal operating conditions.
DEF contamination, electrical corrosion, or extreme temperature exposure are common failure causes.
Yes, frozen DEF can crack the unit’s housing or damage internal sensors.
Cummins DEF Head Units
