Case IH 19525 – Engine Control Module (ECM) or Dosing Control Unit (DCU) / SCR System Controller: DEF/AdBlue temperature sensor voltage is lower than expected.

The system is detecting that the voltage signal returning from the DEF (Diesel Exhaust Fluid) temperature sensor has dropped below the acceptable minimum threshold. This condition almost always indicates a short to ground in the sensor's wiring harness, a pinched wire, or an internal short/failure within the sensor itself.

• Tier 4b
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Steiger (Quadtrac)
• Magnum
• Puma
• Maxxum
• Farmall
• 580N Backhoe Loaders

1. 1

   Visually inspect the wiring harness from the DEF tank header unit to the ECU for pinched wires or rubbing near the exhaust

2. 2

   Perform a short-to-ground test by disconnecting the DEF temperature sensor and ECU connectors, then testing the power and signal wires with a multimeter

3. 3

   Test the resistance of the temperature sensor pins on the DEF header to verify if the sensor has failed internally

1. 1

   Resolve Wiring Issues

   If a pinched wire was found during diagnostics, repair the damaged wire section. Reroute the harness away from pinch points, secure it with zip ties, and reinstall any protective cover plates.

2. 2

   Access the DEF Tank

   If the sensor itself is faulty, clean the area around the top of the DEF tank thoroughly to prevent dirt from falling into the fluid.

3. 3

   Remove the DEF Header

   Disconnect the electrical connector and the DEF fluid lines from the top of the DEF sender unit. Unbolt/unscrew the retaining ring holding the unit in the tank and carefully pull the assembly out.

4. 4

   Install the New Unit

   Insert the new DEF Head Unit/Temperature Sensor assembly into the tank. Secure the retaining ring.

5. 5

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical harness.

6. 6

   Clear Codes

   Connect the Electronic Service Tool (EST), clear the inactive 19525 fault code, and run the machine to verify the sensor is reading the correct DEF temperature and the code does not return.