Case IH 3319 – Engine ECU: DM1DCU SPN2 message - Error in DCU active

The Engine Control Unit (ECU) has received a Diagnostic Message 1 (DM1) over the CAN bus from the Dosing Control Unit (DCU) indicating that the DCU has an active fault. This specifically translates to a DTC control error detected: Urea level in the tank below 5%, or that the DCU is unable to read the level/build pressure, which will lead to an engine derate.

• Case IH Steiger Tractors (350, 400, 450, 500, 550, 600)
• Case IH Magnum Tractors (235–340 Series 4)
• Case IH Axial-Flow Combines (7230, 8230, 9230)

1. 1

   Verify DEF Level: Physically check the DEF tank level. If it is below 5%, the system is operating as designed. Refill the tank with fresh DEF.

2. 2

   Check for Air Leaks: The WEMA (suction pickup unit inside the tank) can leak air into the suction line. Install a clear section of hose between the DEF tank and the DCU to check for air bubbles while the pump is running.

3. 3

   Check the Coolant Control Valve (CCV): If the CCV is stuck open, it can boil the DEF and damage the DCU. Check if the coolant lines running to the DEF tank are excessively hot when they shouldn't be.

4. 4

   Pull DCU-Specific Codes: Use the Case IH Electronic Service Tool (EST) to pull the internal DCU codes. Code 3319 is a generic message; the DCU itself will have a specific 19xxx-series fault code indicating exactly what failed inside the dosing unit.

1. 1

   Preparation

   Turn off the machine and wait at least 10 minutes for the DCU to complete its automatic purge cycle. Disconnect the battery to prevent electrical shorts.

2. 2

   Disconnect Lines

   Locate the DCU (typically mounted to the vehicle frame). Disconnect the DEF supply line, return line, and the electrical wiring harness.

3. 3

   Remove the DCU

   Unbolt the DCU from its mounting bracket.

4. 4

   Install the New DCU

   Mount the replacement Bosch DCU to the frame bracket. OEM guidelines state the M8 mounting screws must be tightened to a torque of 10 ± 2 Nm.

5. 5

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical harness.

6. 6

   Software Programming

   Connect the Case IH EST (Electronic Service Tool) laptop to the machine and flash/program the new module to the vehicle's ECU. The system will not function without this software installation.