Case IH 19532 – DCU (Dosing Control Unit) or Engine ECU (EDC): DEF/AdBlue pressure did not drop when system was evacuated or Back flow line clogged / Reagent dosing valve - short circuit low

When the engine is shut down, the DEF (Diesel Exhaust Fluid) system runs an automatic purge/evacuation cycle. The DEF supply pump reverses flow to pull fluid out of the lines and back into the tank to prevent the fluid from freezing and expanding, which would damage the components. This fault code is triggered when the pressure sensor detects that the fluid pressure did not drop during this evacuation cycle. This typically means the backflow line is clogged, the fluid is frozen, the ventilation valve failed to open, or the dosing valve has an electrical short circuit.

• Tier 4b
• 240 Series Axial-Flow Combines
• Steiger (350, 400, 450, 500, 550, 600)
• Magnum (235–340 Series 4)
• Puma series
• 721F
• 821F
• 921F
• W190C
• W230C

1. 1

   Determine if the DEF/AdBlue solution is frozen in the lines due to cold environmental conditions. If frozen, allow the system to thaw and retest.

2. 2

   Check the DEF dosing injector tip and the mixing chamber for scale build-up or crystallization, which can block fluid flow.

3. 3

   Inspect the DEF backflow line (from the dosing module to the tank) for physical kinks, pinching, or blockages.

4. 4

   Check the dosing valve wiring harness for a short circuit to ground (associated with the P2063 sub-code). Measure the resistance between the dosing valve SIGNAL pin and RETURN pin.

5. 5

   Verify that the ventilation valve is opening properly during the purge cycle.

1. 1

   Verify the Fault

   Confirm the fault code is present and active. If it is inactive, clear the code and return the machine to operation to see if it returns.

2. 2

   Clean the Dosing Valve

   Remove the DEF dosing valve. If scale or crystallization is present on the tip, clean it using only warm water and a clean shop cloth. Caution: Do not use a wire wheel, brass brush, or any abrasive medium, as this will cause permanent damage to the injector tip. Inspect the tip for cracks and replace if damaged.

3. 3

   Clear the Backflow Line

   Disconnect the DEF backflow line. Flush the line with warm water to dissolve any crystallized urea blockages. If the line is permanently obstructed or damaged, replace it.

4. 4

   Repair Wiring (If Applicable)

   If the electrical check revealed a short circuit (P2063), repair or replace the damaged section of the wiring harness leading to the dosing valve.

5. 5

   Replace the DEF Pump (Supply Module)

   If the lines are clear, the dosing valve is clean and electrically sound, and the system still fails to evacuate pressure, the internal reversing valve inside the DEF supply pump has likely failed. The DEF pump/supply module will need to be replaced.