Case IH 19325 – DCU (Dosing Control Unit): UREA Temperature in Tank out of range

The temperature sensor inside the Diesel Exhaust Fluid (DEF) tank is reading a temperature that is outside the permissible or plausible operating range. This can occur due to low DEF fluid levels, a failed DEF tank temperature sensor, or a stuck-open Coolant Control Valve (CCV).

• Tier 4a
• Tier 4b
• Case IH Magnum 235 - 340 (Series 4)
• Case STX Steiger tractors (350 to 600 HP)
• Case IH Puma series
• Case IH Farmall series (Tier 4B)
• Case Construction equipment (e.g., CX series excavators, wheel loaders)

1. 1

   Check DEF fluid level — low fluid levels combined with long running durations can cause returned DEF to overheat the remaining fluid in the tank.

2. 2

   Inspect the Coolant Control Valve (CCV) — verify it is not stuck open or leaking by checking if the coolant lines running to the DEF tank heating unit are warm when they shouldn't be.

3. 3

   Inspect the DEF head unit/sensor wiring harness and connector pins for damaged or loose machine grounds, as well as debris or water inside the connector terminals.

4. 4

   Check the tank heating valve to ensure it is operating normally and is not mechanically blocked open.

1. 1

   Safety First

   Stop the engine and allow the machine to cool completely before starting work. Do not start the engine during the service procedures.

2. 2

   Address the Coolant Control Valve (CCV)

   If diagnostic checks reveal the CCV is stuck open and continuously heating the tank, replace the CCV (heater valve).

3. 3

   Address the DEF Head Unit

   If the CCV is functioning normally and the wiring harness is intact, the DEF tank temperature sensor itself has likely failed. Because the temperature sensor is integrated into the DEF tank sending unit, you must replace the entire DEF Head Unit assembly.

4. 4

   Clear Codes

   After replacing the faulty component, use a diagnostic tool to erase the fault code and run the machine to verify normal operation.