New Holland DCU 19046 – DCU: UREA pressure sensor in box (electrical) | supply voltage error | P204A Reagent - pressure sensor - open circuit

The system has detected an open circuit or a supply voltage error related to the Diesel Exhaust Fluid (DEF/Urea) pressure sensor, which is internally integrated into the DEF supply module (the DEF pump).

• T6 series (T6.120 to T6.175)
• T7 series (T7.170 to T7.260)
• T8 series
• T9 series
• CR series (CR6090 to CR9.90)
• CX series (CX8070, CX8090)
• LM series (LM6.32 to LM9.35)

1. 1

   Inspect the main wiring harness leading to the DEF supply module for chafing, breaks, or melted wires.

2. 2

   Disconnect the DEF pump harness and check for corrosion, bent pins, or pushed-out terminals. DEF fluid is highly corrosive; any fluid intrusion into the connector can cause an open circuit.

3. 3

   Turn the key ON and use a multimeter to verify that the DCU is sending the correct reference voltage and ground to the DEF supply module.

4. 4

   If the external wiring, ground, and voltage supply from the DCU are all intact and within specification, the open circuit is internal to the DEF pump's pressure sensor.

1. 1

   Prepare machine

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

2. 2

   Locate the module

   Locate the DEF supply module (pump), which is typically mounted near the bottom of the DEF tank.

3. 3

   Clean the area

   Clean the outside of the module and the line connections thoroughly with warm water to dissolve any crystallized DEF and prevent contamination of the new unit.

4. 4

   Disconnect lines

   Disconnect the DEF suction, pressure, and backflow lines. Cap the lines immediately to prevent debris from entering the SCR system.

5. 5

   Remove the module

   Disconnect the electrical harness and unbolt the module from its mounting bracket.

6. 6

   Install the new module

   Bolt the new DEF supply module into place, remove the caps, and reconnect the fluid lines and electrical harness.

7. 7

   Programming

   Reconnect the battery. A new DEF supply module will require programming/calibration to the vehicle's DCU/ECU using the New Holland Electronic Service Tool (EST).

8. 8

   Testing

   Clear the DCU 19046 / P204A fault codes. Run a DEF dosing system test via the diagnostic tool to prime the pump, build pressure, and verify there are no leaks or returning codes.