Case IH 19650 – DCU: UREA Tank level error

The system has detected an erroneous CAN message or a 'short circuit low' (SRC low) on the DEF (Diesel Exhaust Fluid / Reagent) tank level sensor circuit, meaning the voltage returning from the sensor is below the minimum acceptable threshold.

• Tier 4a
• Magnum Series (235–340 Series 4)
• Steiger Series (350–600, Quadtrac, Rowtrac)
• Maxxum
• Puma
• Optum
• Axial-Flow Combines (7230, 8230)

1. 1

   Verify that the DEF tank actually has fluid and that the fluid is not frozen, which can skew sensor readings.

2. 2

   Inspect the wiring harness leading to the DEF header unit on top of the tank for chafing, melted wires, or pinched harnesses that could cause a short to ground.

3. 3

   Disconnect the DEF header plug and check for corrosion or bent pins.

4. 4

   Test the sensor circuit with a multimeter for continuity and verify if there is a direct short to ground on the low side of the sensor circuit.

5. 5

   Connect the Case IH EST laptop to read live data from the DEF level sensor and perform a Urea Dosing System Test (UDST) to verify if the sensor is completely dead or reading out of range.

1. 1

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

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

3. 3

   Disconnect the electrical connector from the DEF header.

4. 4

   Mark and disconnect the DEF suction and return fluid lines from the header.

5. 5

   Remove the mounting bolts or unscrew the locking flange ring that secures the DEF header to the tank.

6. 6

   Carefully pull the old DEF header assembly straight up and out of the tank.

7. 7

   Install the new DEF header assembly.

   Ensure the new O-rings/seals are properly seated (newer OEM replacement units often feature doubled-up O-rings on the pickup tubes to prevent air ingress and seal better).

8. 8

   Secure the locking ring or mounting bolts to the specified torque.

9. 9

   Reconnect the DEF fluid lines and the electrical connector.

10. 10

    Reconnect the battery. Turn the key on and use the Case IH EST to clear the fault codes and verify that the tank level is now reading correctly.