DEF / urea tanks for SCR · XLPE tanks of 19–114 L with a header carrying level, temperature and urea-quality sensors, coolant heating and SAE J2044 fittings; in-tank sensors reading by radio frequency or ultrasound
A DEF tank stores the urea solution that a selective catalytic reduction (SCR) system doses into diesel exhaust. Tanks sold as assemblies carry a header or pump module with a level sensor and, in the designs reviewed here, temperature and urea-quality sensing and engine-coolant heating. Ask three things first: what capacity and shape fit the vehicle or machine, which sensors and signal interface the dosing controller expects, and how the tank is heated and plumbed.
Diesel exhaust fluid (urea) storage tanks for SCR aftertreatment with in-tank level sensing: the tank, header or pump-module sensor assembly, heating, fittings and vent. DEF itself, SCR catalysts, dosing pumps and injectors sold separately, and bulk DEF storage and dispensing tanks at filling sites are outside this page.
01
Cummins Emission Solutions describes its urea tank system as a full tank assembly with a header unit and sensors that monitor urea level, temperature and urea quality, with filtration for debris entering the tank, temperature sensing for freeze-prevention control, and tank ventilation to allow expansion and compression across altitudes. It offers 5, 10, 15 and 30 gallon tanks (19, 38, 57 and 114 L), each in portrait or landscape orientation, in cross-linked high-density polyethylene (XLPE), for purging and nonpurging dosing systems on- and off-highway. [1]
The header interfaces listed are a 5/16 in SAE J2044 return fitting, a 3/8 in SAE J2044 suction fitting, 5/8 in hose barbs for coolant inlet and outlet, a 3/8 in hose barb tank vent and a Deutsch electrical connector. Heated pressure and throttle lines run from 0.5 to 6.0 m and suction lines from 0.5 to 2.0 m in 0.5 m steps, in nylon or EPDM, at 12 V or 24 V; the coolant flow control valve is also 12 V or 24 V with a 3/8 in hose barb, and the specification lists an ambient temperature of −40 to 80 °C. [1]
Editorial calculation: the 19 L to 114 L range is a sixfold span in capacity. [1]
Give the supplier the vehicle or machine, the space envelope and orientation, the capacity, the SCR dosing system and whether it purges, the sensor set and signal interface, heating method (coolant or electric), fitting standard and sizes, vent routing, supply voltage, ambient range, and mounting brackets.
02
An FCA service bulletin for 2014–2015 Ram heavy-duty trucks with the 6.7 L Cummins engine describes a radio-frequency level sensor, part of the pump module in the DEF tank, whose signal changes as fluid exposes it to air; the reading goes to the instrument cluster via the dosing control unit. The same pump module fits a 5.7 gal (21.5 L) pickup tank and a 9.25 gal (35 L) cab-chassis tank, which hold about 0.5 gal (1.8 L) and 2.5 gal (9.5 L) above the top of the sensor, so the gauge can read full until that fluid is used. [2]
The bulletin lists level-sensor fault codes P203B (circuit performance), P203C (circuit low) and P203D (circuit high), and cautions that DEF must not contact open electrical connections or harnesses because it is corrosive. [2] SSI Technologies describes its TULC in-tank sensor as measuring temperature, level and fluid quality or concentration by ultrasound, detecting water dilution and contaminants such as diesel, gasoline and oil, programmable for regular or irregular tank shapes, and communicating on J1939 CAN. [3]
Editorial calculation: 1.8 L is about 8% of the 21.5 L tank and 9.5 L about 27% of the 35 L tank. [2]
03
The American Petroleum Institute (API) states that diesel exhaust fluid, also called DEF or AUS 32, "is a 32.5% solution of technically pure urea in purified water", and that it must meet an ISO purity standard for the SCR unit to operate properly. API's voluntary DEF Certification Program licenses marketers whose fluids satisfy "the most recent and applicable edition of ISO 22241". [4] ISO 22241-1 specifies the quality characteristics of the NOx reduction agent AUS 32 for SCR converter systems in motor vehicles with diesel engines; its second edition was published on 12 February 2019, revising the 2006 edition. [5]
The tank assembly is where that purity can be lost or checked. Cummins describes its urea tank header with filtration for debris entering the tank and sensors that monitor urea level, temperature and urea quality [1]. Ask the tank supplier which materials are in contact with the fluid, how the filler and vent keep dirt out, and whether the quality sensor reports concentration against the 32.5% figure API gives [4].
API's page separates AUS 32 for motor vehicles from AUS 40 Marine DEF used in marine, rail and other land-based applications with large combustion engines [4]. State which of the two fluids the tank will hold. SSI Technologies' TULC sensor is one of the sensors this page already cites for DEF tanks [3]; ask any sensor supplier which concentrations its quality reading covers.
Editorial calculation: AUS 40 at 40% urea carries about 1.23 times the urea concentration of AUS 32 at 32.5% (40 ÷ 32.5). [4]
| Item | Published value or wording | Source |
|---|---|---|
| Fluid name | DEF, AUS 32 | API |
| Urea concentration | 32.5% solution of technically pure urea in purified water | API |
| Quality standard | ISO 22241 (ISO 22241-1 specifies quality characteristics of AUS 32) | API; ISO |
| ISO 22241-1 current edition | Edition 2, published 12 February 2019; revises ISO 22241-1:2006 | ISO (Standard Norge catalogue) |
| Marine fluid | Marine DEF, AUS 40, 40% urea solution, to ISO 18611 | API |
| Certification mark | API Diesel Exhaust Fluid Certification Mark for licensed marketers | API |
Values are from API's DEF programme page and the Standard Norge catalogue entry for ISO 22241-1:2019; the full standard was not reviewed.
04
The companies in the manufacturer list below show this product on their own websites. Confirm the legal seller, factory and scope for your order.
Ask any supplier for capacity and usable volume, tank material, dimensions and orientation, sensor technology and the unmeasured volume above the sensor, quality and temperature sensing, signal output or bus protocol, heater type and power, fittings and vent, supply voltage, ambient range, ingress protection of the connector, and validation against your dosing system.
05
This is a functional reference built from the sources cited; it is not one maker's specification.
| Part | Role | Fix in the order |
|---|---|---|
| Tank body | Holds DEF; XLPE in one range. [1] | Capacity; shape. |
| Header or pump module | Carries sensors, filter, fittings. [1] [2] | Interfaces. |
| Level sensor | Reports fluid level to the controller. [2] [3] | Technology; dead zone. |
| Quality and temperature sensors | Check urea composition; freeze control. [1] [3] | Outputs. |
| Coolant heating and valve | Thaw and heat DEF. [1] | Barb size; voltage. |
| Vent | Allows expansion and compression. [1] | Routing. |
06
A DEF tank quotation needs values for your vehicle and SCR system. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Nominal Capacity (L) | e.g. 19, 38, 57, 114 L; 21.5 and 35 L vehicle tanks. [1] [2] | Total and usable. |
| Operating Pressure (MPa) | Tank vented to allow expansion and compression. [1] | Vent design. |
| Operating Temperature (°C) | e.g. ambient −40 to 80 °C listed. [1] | Range. |
| Level Sensor Accuracy (%) | Not stated in the reviewed sources. One design leaves 1.8–9.5 L unmeasured above the sensor. [2] | Accuracy; dead zone. |
| Supply Voltage (V DC) | e.g. 12 V or 24 V. [1] | Voltage. |
| Output Signal (V) | e.g. J1939 CAN on one sensor. [3] | Signal or protocol. |
| Ingress Protection | Not stated in the reviewed sources. | IP rating. |
| Material | e.g. XLPE tank. [1] | Tank and sensor materials. |
| Weight (kg) | Not stated in the reviewed sources. | Empty weight. |
| Connection Thread (mm) | e.g. 5/16 in and 3/8 in SAE J2044 quick connects. [1] | Fittings. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Vehicle or machine: [model; space envelope; orientation] Capacity: [total; usable] SCR system: [dosing unit; purging or not] Sensors: [level; temperature; quality; output or bus] Heating: [coolant; electric; voltage] Fittings: [return; suction; coolant; vent; connector] Environment: [ambient range; IP] Quantity: [pieces; brackets]
These companies list def tank with level sensor on their own websites.
Its website has a product page for def tank with level sensor.
Product scope checked 2026-10-12
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Cummins Emission Solutions lists 5, 10, 15 and 30 gallon (19–114 L) urea tanks. [1]
An FCA bulletin explains that fluid above the top of the level sensor must be used before the reading drops. [2]
SSI describes an ultrasonic in-tank sensor that measures level, temperature and concentration and detects contaminants. [3]
API states that DEF (AUS 32) is a 32.5% solution of technically pure urea in purified water, meeting ISO 22241; Marine DEF (AUS 40) is a 40% solution to ISO 18611. [4]
Sources checked 2026-10-12. Cummins Emission Solutions makes urea tank systems; FCA published a service bulletin on DEF level gauges; SSI Technologies makes an in-tank DEF sensor.
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