New Holland DCU 19298 – DCU: UREA pressure too low at system start / Reagent pump not delivering

The Selective Catalytic Reduction (SCR) system's DEF (Diesel Exhaust Fluid) supply module is failing to build or maintain the required fluid pressure during the system's initialization phase.

• T6 series (T6.140, T6.150, T6.160, T6.175)
• T7 series (T7.170, T7.210, T7.260)
• T8 series
• CR series (CR6090, CR8090, CR9.90)
• CX series (CX8070, CX8090)
• LM series (LM6.32, LM7.42, LM9.35)

1. 1

   Listen for the Pump: Turn the system on and listen to verify if the DEF pump motor can be heard running.

2. 2

   Inspect the DEF Tank: Check the tank for frozen fluid, crystallization, or debris that could block the pickup tube.

3. 3

   Check Lines for Leaks or Blockages: Inspect the DEF feeding line for leaks, kinks, or breaks. A broken line can cause the pump to suck air instead of fluid.

4. 4

   Filter Inspection: Check for a clogged UREA/DEF filter, which is a primary cause of restricted flow and low pressure.

5. 5

   Diagnostic Tool Testing: Use a diagnostic tester to run a Urea Dosing System Test (UDST). Monitor if the pressure drops immediately when injection starts, which indicates internal leakage or a weak pump.

6. 6

   Sensor Plausibility: Verify that the UREA pressure sensor is reading correctly and not storing a secondary plausibility failure.

1. 1

   Inspect and clean the DEF tank

   Ensure no debris is restricting the fluid pickup.

2. 2

   Inspect and replace the return line fitting if necessary

   This fitting contains a return orifice that can become blocked with crystallized DEF.

3. 3

   Replace the DEF pump filter element and O-rings

   A clogged filter is the most common maintenance-related cause of this code.

4. 4

   Replace the entire DEF Supply Module (Denoxtronic pump)

   Perform this step if the filter and lines are clear but the pump still cannot build pressure (or the motor is burnt out/stuck).

5. 5

   Run a Pressure Build Up Operation

   After replacing the filter or the supply module, use the OEM diagnostic software to run this operation to prime the system.

6. 6

   Program/calibrate the new module

   If the entire DEF Supply Module is replaced, the new module will need to be programmed/calibrated to the vehicle's DCU.