Case IH 19080 (F-4334-17) – Engine Control Unit (ECU): DEF/AdBlue under pressure failure

The Selective Catalytic Reduction (SCR) system is unable to build or maintain the required pressure of Diesel Exhaust Fluid (DEF) to properly dose the exhaust stream.

• VESTRUM CVX
• Magnum 180
• Magnum 250
• Magnum 340
• Magnum 380
• Steiger 370
• Steiger 450
• Steiger 500
• Steiger 620
• Puma
• Maxxum
• 7240 Axial-Flow Combine
• 8240 Axial-Flow Combine
• 9240 Axial-Flow Combine
• Austoft 9900
• Patriot
• Trident

1. 1

   Verify the DEF tank has adequate, uncontaminated fluid

2. 2

   Inspect all DEF lines, hoses, and the dosing valve actuator for external leaks or crystallization

3. 3

   Connect the Case IH Electronic Service Tool (EST) and run the Urea Dosing System Test (UDST)

4. 4

   Verify system pressures during the UDST: operating pressure should be 4900 to 6200 millibar (71.1 to 89.9 psi), and evacuation vacuum should be -50 to -300 millibar (-0.72 to -4.35 psi)

5. 5

   Inspect the DEF header (WEMA unit) inside the tank for a cracked pickup tube, which can cause the pump to suck air

1. 1

   Verify Fluid

   Ensure the DEF tank has adequate, uncontaminated fluid.

2. 2

   Address Suction Issues

   If the system fails the evacuation vacuum test or cannot build pressure despite a working pump, remove and inspect the DEF header (WEMA unit). If the pickup tube is cracked, replace the header assembly. (Note: Updated WEMA units feature doubled-up o-rings in the pickup tubes to resolve historical suction issues).

3. 3

   Replace the DEF Pump

   If the header and lines are intact but the pump fails to generate the 71.1–89.9 psi required during the UDST, the DEF dosing pump (supply module) has failed internally and must be replaced.

4. 4

   Clear Codes and Regenerate

   After replacing the faulty component, use the EST to clear the permanent fault code. Run the machine through a drive cycle or forced regeneration (operating at high exhaust temperatures, e.g., over 425 degrees for 30 minutes) to allow the SCR system to verify the repair and exit derate mode.