Case IH 19080 – Engine ECU / Dosing Control Unit (DCU): DEF/AdBlue under pressure failure

The Selective Catalytic Reduction (SCR) system is unable to build or maintain the required Diesel Exhaust Fluid (DEF) pressure to properly dose the exhaust system. Normal operating pressure should be between 4900 to 6200 millibar (71.1 to 89.9 psi). Failure to reach this threshold triggers a warning light and derated power mode.

• Tier 4b
• Axial-Flow Combines 240 Series (7240, 8240, 9240)
• Axial-Flow Combines 150/160 Series
• Axial-Flow Combines 250/260 Series
• Magnum Tractors 200, 250, 280, 310, 340, 380, 400
• Steiger Tractors 370, 420, 450, 470, 500, 540, 580, 620
• Puma Tractors 150, 165, 185, 200, 220
• Trident 5550
• Titan 3040-4540

1. 1

   Verify the DEF tank has adequate fluid and that the fluid is ISO 22241 compliant.

2. 2

   Use the Case IH Electronic Service Tool (EST) to run a Urea Dosing System Test (UDST). Confirm if the system pressure can reach the required 4900 to 6200 millibar (71.1 to 89.9 psi) and check the evacuation pressure (-50 to -300 millibar).

3. 3

   Inspect all DEF pressure lines and hoses for ruptures, leaks, or blockages.

4. 4

   Check the DEF tank sending unit (WEMA unit) to see if the pickup tubes vibrate, rattle, or crack, which causes the pump to suck air.

1. 1

   Clean the Area

   Thoroughly clean the area around the DEF supply module and tank to prevent dirt from entering the SCR system during disassembly.

2. 2

   Replace the DEF Filter

   Drain the housing, remove the old filter, and install a new 70-micron OEM filter.

3. 3

   Inspect/Replace the DEF Header

   If the filter is clean but the system still sucks air, remove the DEF header (WEMA unit) from the tank. Inspect the pickup tubes for cracks and replace the header assembly if damaged.

4. 4

   Replace the DEF Supply Module

   If the filter and header are intact but the pump still fails the EST pressure test, replace the entire DEF Supply Module.

5. 5

   Clear Codes

   Use the EST to clear the code and run the machine through multiple driving/dosing cycles to verify the pressure holds and the machine exits derate mode.