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John Deere QLS Head Unit : OEM DZ128860

JOHN DEERE QLS HEAD UNIT : OEM DZ128860

Shipping ICON

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY ICON

WARRANTY
1M MILES OR 1 YEAR

$1,095.00

CORE CHARGE:

$150.00
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 DZ128860
PART TYPE QLS Head Unit
BRAND Tamerx Diesel Products
ENGINE MAKE John Deere
ENGINE TYPE
YEAR
PART NUMBER DZ128860TX

PRODUCT DESCRIPTION

This is a New, Tamerx QLS Head Unit, Tamerx part number DZ128860TX ( OEM Part Number DZ128860 ). This part is primarily made for a John Deere , and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here

OEM NUMBERS

Primary OEMDZ128860
Additional OEMDZ118670, DZ118681, DZ128844, DZ128845, DZ128860, RM100350

ADDITIONAL DETAILS

CONDITIONNew
UPC / Barcode00840490542174
WEIGHT5.00 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.


Unlock precision, durability, and top-tier emission control with the John Deere QLS Head Unit (OEM DZ128860) — engineered to deliver real-time monitoring of fluid levels, temperature, and quality. Built to Deere’s exacting standards and rugged enough for field duty, this head unit ensures seamless integration with your SCR system, helping prevent derates and maintain compliance under pressure. An essential upgrade for any performance-minded John Deere operator.

PEOPLE ALSO ASKS | BLOG(S)

In modern diesel emission systems, precision is everything — and for John Deere machines using DEF (Diesel Exhaust Fluid), the head unit acts as a critical control and sensing hub. The QLS Head Unit, OEM DZ128860 (Tamerx part DZ128860TX) is not just a sensor; it's your engine’s link to properly dosing, monitoring, and diagnosing the DEF system. A failing or mis-calibrated head unit can lead to emission system faults, check engine lights, or reduced performance — none of which you want in the field.

  • Measures DEF fluid level, temperature, and urea concentration, sending that data back to the ECU

  • Controls dosing and feedback for your SCR (Selective Catalytic Reduction) system, enabling accurate NOx conversion

  • Built to the DZ128860 OEM standard, ensuring correct fit, calibration, and compatibility with John Deere DEF systems

  • Helps prevent fault codes, warning lights, or system derates triggered by incorrect sensor data

  • Designed to resist vibration, thermal stress, and exposure to DEF chemistry

  • Comes with a core return option and is backed by a warranty (1 million miles or 1 year)

Don’t wait for a warning light or performance drop to realize your DEF head is failing. Installing the correct OEM DZ128860 / DZ128860TX QLS Head Unit ensures your emissions loop stays accurate, your SCR system remains effective, and your machine stays clean and compliant — all without surprises in the field.

A QLS (Quality Level Sensor) head unit is responsible for monitoring diesel exhaust fluid (DEF) level, quality, and sometimes temperature to ensure emissions systems operate correctly. When it begins to fail, the vehicle may show noticeable warning signs that affect performance and compliance. Recognizing these symptoms early can help prevent costly repairs or downtime.

Common Signs of a Failing QLS Head Unit

  • Dashboard Alerts
    The check engine light or DEF system warning light may appear due to incorrect sensor signals.

  • False DEF Readings
    The system may show the DEF tank as empty or low even when it’s full, or display full when fluid is low.

  • DEF Quality Warnings
    Alerts for poor-quality DEF may appear, even when you’re using certified, clean fluid.

  • Recurring Fault Codes
    Codes such as DEF level, quality, or temperature sensor faults may be triggered repeatedly.

  • Engine Derate Mode
    If the engine control module (ECM) can’t confirm DEF data, it may reduce power or speed to stay emissions-compliant.

  • Inconsistent System Behavior
    Fluctuating readings or intermittent warnings often point to a failing head unit.

A failing QLS head unit often shows itself through inaccurate DEF readings, repeated warnings, and even reduced engine performance. If you notice these signs, it’s best to have the system inspected promptly. Addressing issues early helps maintain emissions compliance and keeps your vehicle running smoothly.

Inspect for cracks, clean sensor ports, and ensure tight, leak-free connections.

Yes — debris or crystallized deposits can block sensor ports or damage seals.

Extreme heat or freezing conditions may stress seals or sensor operation.

Loose connectors or corroded contacts may lead to sensor errors or signal loss.

John Deere QLS Head Units

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