New Holland 19298 – DCU: Urea Pressure Too Low at System Start

The aftertreatment system's Dosing Control Unit (DCU) has detected insufficient urea (DEF) pressure when the system is initiated. The system is unable to build or maintain the required operating threshold (typically 71.1 to 89.9 psi) at startup, preventing the proper injection of DEF into the exhaust stream. This critical failure in reducing NOx emissions may cause the machine to enter a derated power or limp mode if not rectified.

• T6 Series
• T7 Series
• T8 Series
• T9 Series
• CR6090
• CR7090
• CR8080
• CR8090
• CR9090
• CX8070
• CX8090
• LM Series
• Magnum Series
• Magnum 290
• Magnum 340
• Maxxum Series
• Puma Series
• Steiger Series
• 5130
• 6130
• 7130
• 7230
• 8230
• 9230
• Patriot 4430

1. 1

   Check DEF level to ensure the tank is not empty, which can cause air ingress

2. 2

   Visually inspect all DEF lines and connections between the tank, pump module, and injector for leaks, kinks, restrictions, or physical damage

3. 3

   Check for frozen DEF in the tank and lines, and verify the heating circuit is functioning properly

4. 4

   Inspect DEF quality for contamination or crystallization that could clog filters and lines

5. 5

   Connect an Electronic Service Tool (EST) to run the Urea Dosing System Test (UDST) and monitor if system pressure builds to 4900-6200 millibars (71.1-89.9 psi)

1. 1

   Replace DEF filters

   Replace the main filter on the pump module and the inline suction screen (if equipped) to resolve potential clogs. Prime the system and rerun the UDST.

2. 2

   Test for suction leaks

   Disconnect the main DEF suction line from the tank unit and connect it to an external source of clean DEF. Rerun the UDST. If pressure builds, the fault is in the tank pickup/WEMA unit (e.g., cracked tube or faulty O-ring).

3. 3

   Inspect and test DEF pump module

   Listen for the pump to run during key-on or UDST. If there is no sound, diagnose the electrical circuit (power, ground, motor). If it runs but fails to build pressure with clear restrictions, the pump is likely faulty due to internal leakage.

4. 4

   Check reverting valve

   Use the EST to test the reverting (purge) valve. Ensure it is not stuck open, which would prevent pressure buildup by allowing fluid to bleed back to the tank.

5. 5

   Inspect pressure sensor

   Verify the pressure sensor is providing accurate readings to the DCU, as a faulty sensor can trigger a false low-pressure code.

6. 6

   Replace and program DEF module

   If the DEF pump/dosing module is determined to be faulty, replace it. After replacement, use the Electronic Service Tool to program or calibrate the new module to the machine.