Case IH 3320 – Engine Control Unit (ECU) / EDC: DM1DCU SPN3 message - Error in DCU active / DCU Fault Detected: Urea Tank Below 10%

The Diesel Exhaust Fluid (DEF) / AdBlue level in the tank has dropped below the 10% threshold. The Dosing Control Unit (DCU) has detected this low fluid condition and broadcasted a warning message (DM1DCU) over the CAN bus, which is then logged as an active error. If ignored, this condition will eventually lead to engine derate.

• Magnum (225-380)
• Steiger (350-600)
• Puma (140-240)
• Optum (270-300)
• Maxxum (115-150)
• Patriot 3230
• Patriot 3240
• Patriot 3320
• Patriot 3330
• Patriot 4420
• Patriot 4430
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7240
• Axial-Flow 8240
• Axial-Flow 9240

1. 1

   Visually inspect the DEF/AdBlue tank to confirm if the fluid level is actually below 10%

2. 2

   Use an Electronic Service Tool (EST) to monitor the DEF tank level sensor readings and compare the digital reading to the physical fluid level

3. 3

   Inspect the wiring harness and connector at the DEF tank level sending unit for corrosion, pushed pins, or chafed wires causing a false low-level reading

4. 4

   Check for other active DCU fault codes (such as 3319 for tank below 5%) that might be triggering an inducement or derate

1. 1

   Refill the Tank

   Fill the DEF/AdBlue tank with high-quality, uncontaminated Diesel Exhaust Fluid.

2. 2

   Reset the System

   Turn the ignition key switch OFF, wait for the system to power down completely, and then turn it back ON. This allows the DCU to poll the level sensor and register the new fluid volume.

3. 3

   Test the Sensor

   If the tank is full but the gauge still reads empty and the 3320 code remains active, the DEF level sending unit has likely failed internally.

4. 4

   Replace the Sensor

   Drain the DEF tank below the sensor mounting point (or completely, to flush the tank). Disconnect the electrical connector and DEF lines from the sending unit head, unthread the locking ring/hardware, and remove the faulty sensor. Install the new sensor and reconnect the lines.

5. 5

   Clear Codes

   Connect the EST and clear the inactive fault codes from the Engine ECU and DCU. Run the engine to operating temperature to verify the code does not return.