Case IH 19808 – DCU (Dosing Control Unit): UREA Tank Temperature not plausible with Pump module temperature - SRC Low

The Diesel Exhaust Fluid (DEF / Urea) tank temperature sensor is reporting a temperature that is implausibly low when compared to the DEF pump module temperature. The system expects these two temperature readings to correlate within a specific threshold. When they do not, the system flags the tank temperature sensor as being out of range.

• Tier 4a
• Case IH Steiger & Quadtrac: 350, 370, 400, 420, 450, 470, 500, 540, 550, 580, 600, 620
• Case IH Magnum: 235, 250, 260, 280, 290, 310, 340, 380
• Case IH Puma & Maxxum: 115, 125, 135, 145, 150, 165, 185, 200, 220, 240
• Case IH Combines: 5130, 6130, 7130, 7230, 8230, 9230, and 40/50/60 series

1. 1

   Connect the Electronic Service Tool (EST) and compare the DEF tank temperature reading to the ambient air temperature and the DEF pump module temperature to verify if the sensor is dead.

2. 2

   Inspect the electrical harness and connectors at the DEF header on top of the tank for corrosion, damaged pins, or chafed wires.

3. 3

   Check the Coolant Control Valve (CCV) / Tank Heating Valve to ensure it is not stuck open or closed, and verify if the coolant lines running to the DEF sending unit are warm.

4. 4

   Inspect the DEF tank for dirt, debris, or heavy DEF crystallization that might be interfering with the sensor probe.

1. 1

   Prep the Machine

   Turn off the machine, disconnect the battery, and thoroughly clean the area around the top of the DEF tank to prevent dirt from falling into the tank during removal.

2. 2

   Drain the Tank

   If contamination is suspected, drain the DEF tank completely.

3. 3

   Disconnect Lines

   Carefully disconnect the electrical harness connector and the engine coolant heating lines from the DEF header. Be prepared to catch a small amount of spilled coolant.

4. 4

   Remove the DEF Header

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

5. 5

   Install the New Unit

   Insert the new DEF sender unit into the tank, ensuring the rubber gasket/O-ring is properly seated to prevent leaks. Tighten the locking ring to OEM torque specs.

6. 6

   Reconnect and Refill

   Reconnect the coolant lines and electrical harness. Replace the inline DEF filter while the system is open. Refill the tank with fresh, certified Diesel Exhaust Fluid.

7. 7

   Clear Codes

   Use the EST to clear the 19808 / P205B fault codes. Run the engine up to operating temperature and verify that the DEF temperature readings are now plausible and the code does not return.