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CMI Cummins ISB 6.7L DEF Head Unit

CMI CUMMINS ISB 6.7L DEF HEAD UNIT

Shipping ICON

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY ICON

WARRANTY
1M MILES OR 1 YEAR

$895.00

CORE CHARGE:

$250.00
iCORE DISCLAIMER: The CORE charge is a 30 day hold and will not be processed as long as the CORE is returned within 30 days. If you do not have a CORE or fail to return the CORE within 30 days, the CORE charge hold amount will be processed at that time.

AVAILABILITY IN STOCK
OEM NUMBER CM205532
PART TYPE DEF Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE Cummins
ENGINE TYPE ISB 6.7L
YEAR
PART NUMBER 4310-22-1
APPLICATION NOTES CMI
ADDITIONAL NOTES DEF Header, 40 MICRON, 22"

PRODUCT DESCRIPTION

This is a Remanufactured, Tamerx DEF Head Unit, Tamerx part number 4310-22-1 ( OEM Part Number CM205532 ). This part is primarily made for a Cummins ISB 6.7L, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here

Additional Notes: DEF Header, 40 MICRON, 22"

OEM NUMBERS

Primary OEMCM205532
Additional OEMCM205532

ADDITIONAL DETAILS

CONDITIONRemanufactured
UPC / Barcode00840490540668
WEIGHT8.00 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.


Kick your emissions system into gear with the CMI Cummins ISB 6.7L DEF Head Unit (OEM CM205532) — a high-performance, remanufactured unit tailor-made for Cummins ISB 6.7L engines. With real-time precision in monitoring DEF level, temperature, and quality, it integrates seamlessly into your SCR system to prevent derates and maintain compliance. Rugged, reliable, and backed by Tamerx’s 1,000,000-mile / 1-year warranty, it’s the upgrade your engine deserves.

PEOPLE ALSO ASKS | BLOG(S)

When your vehicle is built on a CMI frame powered by the Cummins ISB 6.7L engine, each component in the emissions system must work flawlessly—especially the DEF head unit. The CMI Cummins ISB 6.7L DEF Head Unit (OEM CM205532) is not just another sensor module—it’s essential for proper monitoring, fluid dosing, and diagnostics. A failure in this unit can trigger costly fault codes, degrade performance, or even force unwanted engine derates.

  • Monitors key parameters of your DEF system: fluid level, temperature, and urea concentration

  • Regulates accurate dosing of DEF into the exhaust stream to support the SCR (Selective Catalytic Reduction) system

  • Built to OEM spec (CM205532) to ensure seamless integration with CMI / Cummins ISB 6.7L applications

  • Helps prevent the dreaded engine derate or warning lamps that stem from faulty readings

  • Designed to endure vibration, thermal cycling, and exposure to DEF fluid chemistry

  • Easy to replace in the field—cutting down on downtime and service costs

  • Backed by a 1,000,000-mile or 1-year warranty when installed by professionals

If your emissions system is acting up—fault codes, reduced power, or unexpected warnings—the DEF head is often the first suspect. Installing the OEM CM205532 unit restores your system’s accuracy, prevents unwelcome surprises, and keeps your CMI Cummins ISB 6.7L platform emissions-compliant and reliable.

The DEF (Diesel Exhaust Fluid) head unit is designed to monitor fluid level, temperature, and quality, ensuring that diesel engines remain compliant with emissions regulations. Because DEF is sensitive to temperature, extreme hot or cold conditions can directly impact how the DEF head unit operates. Understanding these effects helps operators protect their systems and avoid unexpected downtime.

Effects of Temperature on DEF Head Unit Operation

  • Freezing Temperatures
    DEF begins to freeze at around 12°F (-11°C). When this happens, the DEF head unit sensors may temporarily stop providing accurate readings until the fluid thaws.

  • High Heat Exposure
    Excessive heat can degrade DEF fluid quality and cause the sensors inside the head unit to detect abnormal values. Prolonged heat may also damage internal electronics.

  • Temperature Sensor Strain
    Since the head unit relies heavily on its temperature sensor, rapid swings between hot and cold conditions can lead to sensor stress or failure.

  • Crystallization Concerns
    Frequent freeze-thaw cycles or temperature fluctuations can cause DEF to crystallize, which may interfere with sensors inside the head unit.

  • Storage and Parking Impact
    Vehicles parked outdoors in very hot or cold climates often experience more DEF head unit issues compared to those stored in controlled environments.

Temperature plays a critical role in how well the DEF head unit performs. By protecting vehicles from extreme weather, using high-quality DEF, and performing routine system checks, operators can extend the life of the head unit and reduce the risk of performance issues.

The quality sensor detects off-spec conditions and may trigger fault codes or reduce dosing to protect the system.

With proper maintenance and use of quality DEF, it can last multiple years and tens of thousands of operating hours before degradation.

Erratic sensor readings, repeated DEF system warnings, engine derate, or fault codes often signal its failure.

Flush gently with clean, spec-grade DEF, avoid strong solvents, and carefully clean around sensor openings.

Cummins DEF Head Units

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