Case IH 19114 – Engine Control Module (ECM) / Dosing Control Unit (DCU): DEF/AdBlue tank temperature sensor plausibility min threshold

The system's plausibility check has failed because the temperature reading from the DEF (Diesel Exhaust Fluid) tank sensor is abnormally low when compared to the ambient/atmospheric temperature sensor.

• Tier 4b
• 240 Series Axial-Flow Combines
• Farmall
• Maxxum (115-150)
• Puma (150-240)
• Optum (270-300)
• Steiger
• Magnum
• WD Series Windrowers (WD1204, WD1504, WD1904, WD2104, WD2304, WD2504)

1. 1

   Verify the ambient/atmospheric air temperature sensor is reading correctly, as this is a plausibility code comparing DEF tank temp to outside air.

2. 2

   Inspect the wiring harness and connector at the DEF tank head unit for loose contacts, damaged wires, or rodent damage.

3. 3

   Check connector terminals for debris, corrosion, or water intrusion (often caused by aggressive pressure washing).

4. 4

   Use a diagnostic service tool to read live data for the DEF tank temperature. Look for extreme default values (like -40°C) or wild fluctuations indicating an open or shorted circuit.

1. 1

   Safety First

   Stop the engine, turn off the battery disconnect, and allow the machine and exhaust system to cool completely before starting work.

2. 2

   Clean the Area

   Thoroughly clean the top of the DEF tank around the DEF head unit to prevent dirt from falling into the tank during removal.

3. 3

   Disconnect Harnesses

   Unplug the electrical connector to the DEF head unit. Disconnect the DEF suction and return lines (be prepared to catch minor fluid spills).

4. 4

   Test the Circuit

   Back-probe the connector to test the resistance of the temperature sensor. If the resistance is out of specification (indicating an internal open or short), the sensor must be replaced.

5. 5

   Replace the Sensor/Head Unit

   Remove the mounting ring/bolts, pull the old head unit out of the tank, and install the new unit with a new gasket.

6. 6

   Reassemble and Clear Codes

   Reconnect the fluid lines and electrical harness. Turn on the machine, use a diagnostic tool to clear the 19114 fault code, and run the engine to verify the DEF temperature is now reading plausibly.