Case IH 19048 (F-4334-04) – DCU (Dosing Control Unit): DEF/AdBlue supply module pump motor pressure sensor voltage is lower than expected.

The system has detected that the voltage signal from the internal pressure sensor inside the DEF (Diesel Exhaust Fluid) supply module is falling below the minimum expected threshold. This typically indicates an electrical short to ground, an open circuit, or a complete internal failure of the pressure sensor itself. Because of this, the system cannot verify that the DEF pump is building adequate pressure for the Selective Catalytic Reduction (SCR) system, which will eventually lead to an engine derate.

• VESTRUM CVX
• Magnum (180–370, Series 4)
• Steiger (350–600 NA)
• Rowtrac
• Puma (130–215)
• Maxxum (110–140)
• Farmall (95A–140A, 115U)
• Axial-Flow 240 Series
• 5130–9230 Series
• Patriot (2250–4430)
• Titan
• Farmlift Telehandlers (632–935)

1. 1

   Inspect the wiring harness connecting the tractor to the DEF Supply Module/DCU for chafed wires, corrosion, or bent pins that could cause a short circuit low or open circuit.

2. 2

   Check the DEF suction tubes and supply lines for cracks or leaks that could draw air and prevent the pump from building pressure.

3. 3

   Ensure the DEF inline filter is not completely obstructed.

4. 4

   Use the Case IH Electronic Service Tool (EST) to monitor the live voltage of the DEF pressure sensor. If voltage is flatlined at 0V or below minimum threshold, the internal sensor has failed.

1. 1

   Preparation

   Turn off the ignition, disconnect the battery, and allow the SCR system to complete its purge cycle (wait at least 5-10 minutes after shutdown).

2. 2

   Drain/Disconnect

   Relieve any residual pressure. Disconnect the DEF supply and return lines from the DEF Supply Module. Cap the lines to prevent crystallization and contamination.

3. 3

   Electrical Disconnect

   Unplug the main wiring harness connector from the DCU.

4. 4

   Removal

   Unbolt the DEF Supply Module/DCU from its mounting bracket and remove the unit.

5. 5

   Installation

   Mount the new DEF Supply Module. Reconnect the DEF lines and the electrical harness.

6. 6

   Software Programming

   The new Dosing Control Unit (DCU) requires software installation and calibration. You must use the Case IH Electronic Service Tool (EST) to program the new module to the vehicle's CAN bus system and clear the fault codes. Note: CNH documentation states that passwords/programming access may require troubleshooting verification via the ASSIST portal.