Case IH 19807 – DCU (Dosing Control Unit): UREA Tank Temperature not plausible with Pump module temperature - SRC High: diagnostic value UREA temperature too high - P205B Reagent - tank temperature sensor (temperature of the Reagent - solution in the tank) - out of range.

The system has detected that the temperature reading coming from the Diesel Exhaust Fluid (DEF/Urea) tank temperature sensor is implausibly high when compared to the temperature reading at the DEF pump module. Because the sensor is reporting a value outside of its normal physical operating range, the system flags it as a failure. This is almost always caused by a failed temperature sensor inside the DEF tank, a short circuit in the wiring, or a damaged connector.

• Tier 4a
• Steiger Series: 350, 370, 400, 420, 450, 470, 500, 540, 550, 580, 600, 620
• Magnum Series: 235, 250, 260, 280, 290, 310, 340, 380
• Puma & Maxxum Series: 115, 125, 150, 165, 185, 200, 220, 240
• Combines: 5130, 6130, 7130, 7240, 8240, 9240

1. 1

   Inspect the DEF tank for heavy contamination, crystallization, or debris that could interfere with the sensor.

2. 2

   Inspect the wiring harness and the electrical connector at the DEF header unit on top of the tank. Look for corroded pins, moisture intrusion, or chafed wires that could cause a short circuit (which mimics a 'too high' temperature reading).

3. 3

   Use a diagnostic scan tool to view the live DEF tank temperature data. Compare the tank temperature reading to the DEF pump module temperature and ambient temperature. If the tank temperature is pegged at an unrealistically high number while the machine is cold, the sensor has failed.

4. 4

   Verify that the power and ground signals are correctly reaching the DEF header unit to rule out a broken harness.

1. 1

   Prep the Machine

   Turn off the ignition and disconnect the battery or turn off the master disconnect switch to prevent electrical spikes.

2. 2

   Clean the Area

   Thoroughly clean the top of the DEF tank and around the DEF header unit to prevent dirt or debris from falling into the tank during removal.

3. 3

   Disconnect Lines

   Carefully disconnect the electrical connector from the DEF header. Disconnect the DEF suction, return, and coolant heating lines. Note: Have a catch pan ready, as some fluid will leak from the lines.

4. 4

   Remove the Header

   Unscrew the mounting bolts or the locking ring securing the DEF header to the tank. Carefully pull the long header assembly straight up and out of the tank.

5. 5

   Install the New Part

   Insert the new DEF header assembly into the tank. Ensure the rubber O-ring/gasket is properly seated to prevent leaks and contamination. Secure the locking ring or bolts.

6. 6

   Reconnect

   Reattach the DEF fluid lines, coolant lines, and the electrical connector.

7. 7

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic scan tool to clear fault code 19807 (P205B).

8. 8

   Test

   Start the machine and monitor the live DEF temperature data to ensure it is now reading plausibly and the code does not return.