Case IH 19336 – DCU (Dosing Control Unit): DEF/AdBlue general pressure check failure

The DEF pump module's internal heating circuit has an open circuit (P20C5). Because the internal heater fails to thaw the frozen DEF fluid in time, the system cannot build the required pressure during its detection mode.

• Tier 4b
• Magnum 235–340 (Series 4)
• Steiger 350–600
• Quadtrac 450–600
• Puma series
• Maxxum series
• Farmall series
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• 130/140/150 series combines
• Patriot sprayers
• Farmlift telehandlers

1. 1

   Verify if the fault is currently active; if inactive, the system may have simply taken too long to thaw in extreme cold but is now functioning.

2. 2

   Inspect the wiring harness between the DEF pressure sensor, the DEF pump module heater, and the DCU/ECU for tight, undamaged connectors, pushed out or corroded pins, and test for continuity.

3. 3

   Measure the DEF concentration to ensure it is exactly 32.5% high-grade urea and 67.5% distilled water.

4. 4

   Remove the dosing injector and inspect the tip and the mixing chamber for white scale deposits.

5. 5

   Test the internal heating element of the DEF pump module for an open circuit (verifying the P20C5 condition).

1. 1

   Clean the Injector

   If white scale build-up is found on the dosing injector tip or in the mixing chamber, clean it thoroughly.

2. 2

   Replace DEF Fluid

   If the DEF concentration is incorrect or contaminated, drain the tank and refill with fresh, correct-spec DEF/AdBlue.

3. 3

   Repair Wiring

   If continuity tests fail between the pump module and the DCU, repair or replace the damaged wiring harness or connectors.

4. 4

   Replace the DEF Pump Module

   If the wiring is intact but the internal heater has an open circuit (P20C5), the DEF pump module (dosing module) has failed internally and must be replaced.

5. 5

   Program and Test

   Program the replacement DEF pump module to the vehicle after installation, clear the codes, bring the engine to operating temperature, and run under load until the ECU determines the Selective Catalytic Reduction (SCR) system is operating properly.