New Holland DCU 19157 – DCU (Dosing Control Unit): UREA Pump speed | Hall sensors defect | P208B Reagent-pump not delivering

This code indicates a failure within the Diesel Exhaust Fluid (DEF) delivery system. The Dosing Control Unit (DCU) has determined that the internal Hall effect sensors, which monitor the speed of the urea pump motor, are defective. The fault is triggered when the control module receives low-level output signals from all three Hall sensors for more than 7 seconds, meaning the pump cannot verify its operating speed and is failing to deliver the reagent (DEF).

• T6.120
• T6.140
• T6.150
• T6.160
• T6.175
• T7.170
• T7.200
• T7.210
• T8 series
• T9 series
• CX5090
• FR450

1. 1

   Inspect the wiring harness and connectors at the DEF Supply Module for physical damage, loose machine grounds, pushed-out connector pins, or water/debris ingress

2. 2

   Ensure the DEF tank and lines are not frozen, as solid fluid can mechanically block the pump and throw speed deviation errors

3. 3

   Use a diagnostic scan tool to monitor the DEF pump speed sensor outputs to verify if signals return to normal

4. 4

   Check the DEF pump main filter for severe clogging, which can restrict flow and cause pump delivery issues

1. 1

   Turn off the machine and disconnect the battery ground.

   Ensure the machine is powered down before beginning the repair.

2. 2

   Locate the DEF Supply Module (Urea Pump) assembly.

   This is typically mounted near the DEF tank.

3. 3

   Clean the area around the pump.

   This prevents dirt from entering the DEF lines during disassembly.

4. 4

   Disconnect the electrical harness from the DEF pump.

   Carefully unplug the connector.

5. 5

   Disconnect the suction, backflow, and pressure lines.

   Note: Be prepared to catch residual DEF fluid; do not let it spill on electrical connections as it is highly corrosive.

6. 6

   Unbolt and remove the defective DEF Supply Module.

   Remove the mounting hardware to free the pump.

7. 7

   Install the new DEF Supply Module.

   Torque the mounting bolts to OEM spec.

8. 8

   Reconnect the fluid lines and the electrical connector.

   Ensure the fluid lines click/lock into place.

9. 9

   Reconnect the battery and clear fault codes.

   Turn the key on and use a diagnostic tool to clear the DCU 19157 / P208B fault codes.

10. 10

    Run a 'Pressure Build-Up' or 'DEF System Prime' test.

    Use the diagnostic tool to bleed the system and verify the pump is delivering fluid correctly.