Case IH 19649 – DCU (Dosing Control Unit): UREA Tank level error – Level over CAN: SAE J1939 no Signal available / Level sensor connected directly: Sensor Supply error (Open Circuit)

The code indicates a critical failure in the Selective Catalytic Reduction (SCR) system's ability to read the Diesel Exhaust Fluid (DEF / Urea) level. This is typically caused by a short to power in the wiring harness, a failed internal resistor/float in the DEF tank level sensor, or corrosion inside the DEF header unit.

• Tier 4a
• Tier 4b
• Magnum 225
• Magnum 235
• Magnum 250
• Magnum 255
• Magnum 260
• Magnum 280
• Magnum 290
• Magnum 310
• Magnum 315
• Magnum 340
• Magnum 370
• Magnum 380
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 470
• Steiger 500
• Steiger 540
• Steiger 550
• Steiger 580
• Steiger 600
• Steiger 620
• Quadtrac 350
• Quadtrac 400
• Quadtrac 450
• Quadtrac 470
• Quadtrac 500
• Quadtrac 540
• Quadtrac 550
• Quadtrac 580
• Quadtrac 600
• Quadtrac 620
• Puma 140
• Puma 150
• Puma 165
• Puma 185
• Puma 200
• Puma 220
• Puma 240
• Optum 270
• Optum 300
• Maxxum 115
• Maxxum 125
• Maxxum 135
• Maxxum 145
• Maxxum 150
• Axial-Flow Combine 7230
• Axial-Flow Combine 8230
• Axial-Flow Combine 9230
• Patriot Sprayer 3230
• Patriot Sprayer 3330
• Patriot Sprayer 4430

1. 1

   Inspect the wiring harness between the DCU and the DEF tank header unit for chafing, melted wires, or pinch points that could cause a short circuit to power (12V)

2. 2

   Disconnect the DEF level sensor connector and check the pins for corrosion, moisture, or DEF crystallization, which can bridge pins and cause a short circuit

3. 3

   With the key ON, use a multimeter to verify the 5V reference and ground at the sensor connector. Check the signal wire for continuity to the DCU and ensure it is not shorted to the power supply wire

4. 4

   Ensure the DEF fluid is not contaminated, as poor quality fluid or contamination can cause chemical reactions that destroy the sending unit sensor

1. 1

   Power Down

   Turn off the machine and disconnect the battery to reset the electronic control systems and prevent electrical spikes.

2. 2

   Access the DEF Tank

   Locate the DEF tank header unit (usually mounted on the top of the DEF tank). Clean the area thoroughly to prevent dirt or debris from falling into the tank.

3. 3

   Disconnect Lines

   Carefully disconnect the electrical connector and the DEF fluid suction/return lines from the top of the header unit.

4. 4

   Remove the Sensor

   Remove the mounting bolts or the retaining lock ring holding the DEF header unit in place. Carefully pull the entire DEF header unit (which houses the level sensor, temperature sensor, and pickup tubes) straight up and out of the tank.

5. 5

   Install New Unit

   Insert the new DEF header unit into the tank, ensuring the rubber O-ring/gasket is properly seated to prevent leaks. Secure the mounting bolts or lock ring.

6. 6

   Reconnect

   Reconnect the DEF fluid lines and the electrical connector. Reconnect the tractor's battery.

7. 7

   Clear Codes

   Turn the key ON. Use a diagnostic scan tool (such as the Case IH EST or Jaltest) to clear the DCU fault codes. If a tool is unavailable, some systems will self-heal and clear the active code after a few key cycles once a valid sensor signal is detected.