New Holland DCU 19038 – DCU: Sensor supply 2 (5V internal; for UREA pressure sensors) | Supply voltage too low | Reagent -pressure sensor -short circuit low.

The 5-volt reference circuit that powers the UREA (DEF) pressure sensor has experienced a voltage drop below the acceptable threshold. This is almost always caused by a short circuit to ground, either within the wiring harness or internally inside the pressure sensor itself.

• T6 Series
• T7 Series
• T8 Series
• T9 Series
• CX Series

1. 1

   Visually inspect the DEF tank and dosing pump area for physical damage, DEF leaks, or white crystallization that could cause a short.

2. 2

   Inspect the wiring harness between the DCU and the UREA pressure sensor for chafed wires rubbing against the frame, melted insulation from exhaust heat, or corroded pins.

3. 3

   Disconnect the UREA pressure sensor, turn the key ON, and measure the voltage at the 5V supply pin on the harness side. If voltage returns to normal, the sensor is internally shorted. If voltage remains low, the harness is shorted.

1. 1

   Disconnect Power

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

2. 2

   Repair Wiring

   If the diagnostic tests revealed a harness short, repair the damaged section of the wiring or replace the pigtail connector. Ensure all repairs are sealed with heat-shrink tubing to prevent moisture/DEF ingress.

3. 3

   Replace the Sensor/Module

   If the sensor is internally shorted, it must be replaced. Remove the DEF lines and electrical connectors, unbolt the old DEF Pump/Dosing Module assembly, and install the new one.

4. 4

   Reprogramming

   If the entire DEF Dosing Module is replaced, the new module will likely need to be programmed/calibrated to the vehicle's ECU using a New Holland diagnostic tool (EST).

5. 5

   Clear Codes

   Reconnect the batteries, clear the DCU 19038 and P204C fault codes, and run a manual stationary regeneration or DEF system test to verify that the pump builds pressure without triggering the code.