Case IH 19749 – DCU (Dosing Control Unit): P208B Reagent-pump - Not delivering

The Diesel Exhaust Fluid (DEF) / Urea Reagent Pump is not delivering fluid to the Selective Catalytic Reduction (SCR) system as commanded. The system monitors the pump motor speed deviation; if the difference between the commanded pump speed and the monitored pump speed exceeds 300 RPM, this DTC sets, and the SCR system shuts down until the next key cycle.

• Tier 4a
• Magnum Tractors: 180, 200, 220, 235, 240, 250, 280, 310, 340, 380
• Steiger Tractors: 350, 370, 400, 420, 450, 470, 500, 540, 580, 600, 620
• Puma Tractors: 140, 150, 165, 185, 200, 220, 240
• Maxxum Tractors: 115, 125, 135, 145, 150
• Combines: 5140, 5150, 6140, 6150, 7140, 7150, 7240, 8240, 9240
• Patriot Sprayers: 2250, 3240, 3340

1. 1

   Check the electrical connector at the DEF pump to ensure it is not unplugged, corroded, or damaged.

2. 2

   Check the power and ground circuits to the DCU and the DEF pump using a multimeter. Place the power and ground wires under a load during testing, as open-circuit voltages can show false positives.

3. 3

   Inspect the DEF supply and backflow lines for physical obstructions, kinks, or freezing that could cause the pump motor to block or fail to build pressure.

4. 4

   Ensure the DEF fluid is clean and free of crystallization or contamination, which can destroy the pump internals.

1. 1

   Clear Codes

   Clear the fault codes and perform a key cycle to see if the code is a hard fault or intermittent.

2. 2

   Resolve Electrical/Plumbing Issues

   If the load test reveals a voltage drop, repair the wiring harness. If lines are blocked, flush or replace the DEF lines.

3. 3

   Replace the DEF Pump

   If the wiring and lines are intact, the pump's internal motor or Hall sensor has failed. Remove the DEF lines and electrical connectors from the dosing module, unbolt the unit from its mounting bracket, and install the replacement module.

4. 4

   System Healing/Regeneration

   After replacing the pump, the tractor may still be in a derated state. You must run the machine under a heavy load (exhaust temps over 425°F) for at least 30 minutes to allow the SCR system to run a complete dosing cycle, verify the repair, and "heal" itself to clear the derate.