Case IH 19325 (DTC 17AA) - ECU – DCU (Dosing Control Unit) / Engine ECU (EEM): DEF/AdBlue tank temperature sensor plausibility max threshold

The temperature reading coming from the DEF (Diesel Exhaust Fluid) tank sensor is outside the permissible physical range (implausible or too high). The system's monitoring logic has detected that the temperature value being reported does not align with expected operating conditions, which can prevent the SCR (Selective Catalytic Reduction) system from properly managing DEF dosing and defreezing modes.

• MAXXUM T4E
• Magnum (235-340 Series 4, 380)
• Steiger (350-600)
• Puma
• Maxxum
• Optum
• Farmall
• Axial-Flow 240 Series (7240, 8240, 9240)
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130

1. 1

   Check for a loose contact in the sensor wiring harness at the DEF tank header.

2. 2

   Test the wiring between the DEF tank sending unit and the DCU for defects, such as an open circuit, short to ground, or short to battery.

3. 3

   If the wiring harness and connectors are intact and providing proper voltage/ground, verify the sensor itself (integrated into the DEF tank sending unit/header).

1. 1

   Turn off machine and disconnect battery

   Turn off the machine and disconnect the battery to ensure safety while working on the electrical and DEF systems.

2. 2

   Disconnect electrical harness

   Locate the DEF tank and disconnect the electrical harness connector from the top of the DEF sending unit (header).

3. 3

   Disconnect DEF fluid lines

   Disconnect the DEF fluid lines from the header (be prepared to catch any minor fluid spills and ensure no dirt enters the open lines).

4. 4

   Remove mounting hardware

   Remove the mounting hardware/lock ring securing the DEF sending unit to the tank.

5. 5

   Extract old sending unit

   Carefully extract the old DEF sending unit assembly from the tank.

6. 6

   Install new sending unit

   Install the new DEF sending unit, ensuring the gasket/seal is properly seated to prevent leaks or contamination.

7. 7

   Reconnect lines and harness

   Reconnect the DEF fluid lines and the electrical harness.

8. 8

   Reconnect battery

   Reconnect the battery and turn the key to the ON position.

9. 9

   Clear fault codes

   Use a diagnostic tool (such as Jaltest or the CNH Electronic Service Tool) to save the error log and then erase the active/stored fault codes.

10. 10

    Verify repair

    Run the machine to verify that the DEF temperature reads accurately and the code does not return.