Case IH 19325 (F-3031-20) - ECU – DCU (Dosing Control Unit) or Engine ECU: DEF/AdBlue tank temperature is not plausible - temperature too high compared to atmospheric temperature

The DEF tank temperature is too high compared to atmospheric temperature. This can occur if the DEF tank runs low and cannot dissipate heat from the dosing module, or if the engine coolant heating loop continuously flows hot coolant through the DEF tank due to a mechanical or routing failure.

• VESTRUM CVX
• Magnum tractors (235-340 Series 4, 290)
• Steiger tractors (350-600)
• Puma tractors
• Austoft 9900 sugarcane harvesters
• Wheel Loaders (721F, 821F, 921F)
• Excavators (CX220E)

1. 1

   Check the Coolant Control Valve (CCV) / Heater Control Valve to ensure it is not stuck open or leaking hot engine coolant into the DEF heating loop

2. 2

   Check DEF hose routing to verify the heater lines are connected correctly and not installed backward

3. 3

   Check DEF fluid level to ensure the tank is not running empty, as low fluid volume heats up much faster during normal dosing module cooling cycles

4. 4

   Inspect wiring harnesses and connectors at the DEF tank sender unit and ECU for damaged, bent, or pushed-out pins, corroded terminals, or broken wires

5. 5

   Perform a sensor plausibility check using a diagnostic tool to compare the DEF tank temperature reading against the ambient air temperature sensor on a cold machine

1. 1

   Fill the DEF Tank

   If the tank is low, fill it with fresh DEF/AdBlue to increase the thermal mass and see if the temperature normalizes.

2. 2

   Test the Heater Control Valve

   Command the Coolant Control Valve via the diagnostic service tool. If the valve is stuck open or leaking coolant into the DEF heating loop, replace the valve.

3. 3

   Correct Hose Routing

   If the hoses were connected incorrectly (e.g., the line with the red band is not connected to the correct top tube running to the engine head), swap them to the correct orientation. Note: If the hoses were reversed for a long time, the valve may have been damaged and might also need replacement.

4. 4

   Repair Wiring

   If any breaks or shorts are found in the harness between the DEF tank sender and the ECU, repair the wiring or replace the connector.

5. 5

   Replace the Sender Unit

   If the CCV is functioning properly, the wiring is intact, and the temperature reading remains implausible, the temperature sensor inside the DEF tank is likely failed. Replace the DEF tank sender unit.

6. 6

   Clear Codes

   Erase the fault code using the diagnostic tool and operate the machine while monitoring the DEF temperature to verify the repair.