New Flyer Cummins DEF Head Unit
NEW FLYER CUMMINS DEF HEAD UNIT
ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY
WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a New, Tamerx DEF Head Unit, Tamerx part number 6366920 ( OEM Part Number 6366920 ).This part is primarily made for a Cummins , production years 2017-2022, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
OEM NUMBERS
| Primary OEM | 6366920 |
| Additional OEM | 6366920 |
ADDITIONAL DETAILS
| CONDITION | New |
| UPC / Barcode | 00840490542341 |
| WEIGHT | 5.00 LBS |
SHIPPING OPTIONS
Ship Weight : 5.00 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 reliability, the New Flyer Cummins DEF Head Unit OEM 6366920 is designed to ensure proper Diesel Exhaust Fluid system function in New Flyer buses powered by Cummins engines from 2017 to 2022. This genuine OEM component is manufactured to exact factory standards, providing accurate fitment, dependable operation, and seamless communication within the emissions system. By maintaining consistent DEF flow and monitoring, it helps support emissions compliance and steady engine performance in demanding transit applications. Its durable construction is engineered to withstand the harsh conditions of daily bus service, offering long-lasting reliability. For fleet operators and maintenance professionals, this DEF head unit delivers OEM-backed quality and trusted dependability to keep New Flyer buses performing at their best.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2017 | Cummins | |||||
| 2018 | Cummins | |||||
| 2019 | Cummins | |||||
| 2020 | Cummins | |||||
| 2021 | Cummins | |||||
| 2022 | Cummins | |||||
PEOPLE ALSO ASKS | BLOG(S)
The DEF Head Unit OEM 6366920 used in New Flyer buses with Cummins engines is the sensor and fluid interface module for the Diesel Exhaust Fluid (DEF) tank. Mounted directly on the tank, it plays a vital role in the vehicle’s emissions control / SCR (Selective Catalytic Reduction) system.
Core Role & Functions
- Monitor DEF Level
- The head unit senses how much DEF remains in the tank, providing the vehicle’s control system with real-time fluid level data so it can warn the operator when refilling is needed.
- Temperature Sensing
- It tracks the temperature of the DEF fluid to detect freezing or overheating, which can affect dosing accuracy and system reliability.
- Fluid Routing / Header Function
- The head unit acts as a header: it provides the pathway(s) for pulling DEF from the tank (pickup) into the dosing/injection side, and may also include return paths for unused fluid.
- Filtration / Protection
- Built into the head unit is usually a fine filter or strainer to catch particulates, crystals, or debris before they reach sensitive DEF injection components.
- Signal Communication
- It relays sensor data (level, temperature, and possibly more) to the engine’s control module (ECM), allowing the system to manage dosing, detect faults, and protect emission components.
In short, the New Flyer DEF Head Unit OEM 6366920 is the “bridge” between the DEF tank and the engine’s emissions control system. Without it, the system would not know the fluid status, could not regulate dosing properly, and could face faults or derating due to lack of feedback.
The DEF (Diesel Exhaust Fluid) Head Unit is a vital part of a truck’s emissions system. It measures DEF level, temperature, and quality, helping the vehicle maintain compliance and efficiency. Like any component exposed to fluid and heat, the DEF head unit has a limited lifespan — but with proper care, it can last for years.
Average Lifespan of a DEF Head Unit
Under normal operating conditions, a DEF head unit typically lasts 5 to 7 years. In well-maintained systems, it can last even longer. However, several factors — including fluid quality, environment, and maintenance habits — play a major role in how long it lasts.
Factors That Affect Lifespan:
- DEF fluid quality –
- sing certified DEF prevents contamination and sensor damage.
- Storage conditions
- Extreme heat or freezing temperatures can shorten lifespan.
- Handling practices
- Dirty or unsealed containers allow debris into the DEF tank.
- Vehicle duty cycle
- Heavy use and high idle time put more strain on the unit.
- Maintenance
- Regular inspections catch early signs of buildup or corrosion.
How to Maximize Lifespan
You can help your DEF head unit reach its full life expectancy by:
- Using fresh, uncontaminated DEF from sealed containers
- Avoiding exposure to direct sunlight or freezing conditions
- Inspecting the DEF tank regularly for crystallization or contamination
- Following OEM maintenance schedules for your emissions system
A DEF Head Unit generally lasts 5 to 7 years, but consistent maintenance and proper fluid handling can extend its life significantly. Preventive care not only saves money but also helps avoid downtime and unexpected derate events.
It sends DEF level and quality data to the Engine Control Module (ECM) for emission control adjustments.
Yes, a failing head unit can send false signals that show incorrect fluid levels or trigger fault codes.
Yes, freezing can damage the internal sensors or connectors if the DEF tank is not properly maintained.
It’s recommended to inspect it during every scheduled maintenance or DEF filter replacement.
Cummins DEF Head Units
