Case IH 19757 – DCU (Dosing Control Unit): Group error path UREA injection control – Error belonging to group UREA Injection control – P208B Reagent-pump - Not delivering.

The Selective Catalytic Reduction (SCR) system has detected that the Diesel Exhaust Fluid (DEF) / Urea pump is failing to deliver the required fluid pressure or volume. The system monitors the pump motor speed deviation; if the difference between the commanded pump speed and the monitored speed exceeds acceptable limits, the system flags the pump as not delivering or unplugged.

• Tier 4b
• Tier 4a and newer
• Case IH Steiger Series
• Steiger 450
• Case IH Magnum Series
• 235-340 Series 4
• Puma
• Optum

1. 1

   Inspect the DEF tank for frozen fluid, crystallization, or debris that could be starving the pump.

2. 2

   Check the power and ground circuits to the DCU and the DEF pump under a load with a multimeter to check for high resistance.

3. 3

   Inspect the wiring harness for the DEF pump to ensure it is not physically unplugged, corroded, or suffering from damaged pins.

4. 4

   Check the DEF suction, pressure, and backflow/return lines for blockages, kinks, or leaks, including a clogged return line orifice.

1. 1

   Resolve Wiring/Plumbing Issues

   If the diagnostic checks reveal high resistance in the wiring, repair the harness. If DEF lines are clogged or leaking, replace the affected lines or fittings.

2. 2

   Run System Tests

   Connect the CNH EASY diagnostic tool and command a 'Pressure Build Up Operation' or dosing test to verify if the pump can physically build pressure.

3. 3

   Replace the Pump

   If the wiring is sound, the tank is clean, and the pump still fails to deliver fluid or fails the speed deviation test, the internal pump motor is likely damaged. Replace the DEF Reagent Pump Assembly.

4. 4

   Clean and Service

   Whenever replacing the DEF pump, you must clean the DEF tank and replace the main DEF filter to prevent debris from destroying the new pump.

5. 5

   System Healing

   After the repair is completed and codes are cleared, bring the engine up to operating temperature and run under a heavy load (exhaust temperatures typically need to exceed 425°F) for at least 30 minutes. This allows the SCR system to run its self-checks, verify that the DEF system is operating properly, and clear the fault/derate condition.