Case IH 19799 – Engine Control Module (ECM) or Denoxtronic Control Unit (DCU): SCR Inducement: Warning, triggered by DEF/AdBlue Quality fault

The Selective Catalytic Reduction (SCR) system has detected that the Diesel Exhaust Fluid (DEF) does not meet the required concentration (typically 32.5% urea) or is contaminated. This is an inducement warning that will escalate to Level 1 (Torque reduction) or Level 3 (Creep mode) if not resolved.

• Tier 4b
• 240 Series Axial-Flow Combines
• Farmall Tractors
• Puma and Maxxum Series Tractors
• Steiger Tractors
• STM N Series Loaders

1. 1

   Test the DEF Fluid: Use a DEF refractometer to test the fluid currently in the tank. It must read exactly 32.5% urea concentration.

2. 2

   Inspect for Contamination: Check the DEF tank for dirt, debris, water, or accidental diesel fuel contamination.

3. 3

   Check for Crystallization: Inspect the DEF tank, lines, and dosing module for white, crystallized urea buildup, which can block flow and cause false readings.

4. 4

   Inspect the DEF Quality Sensor / Head Unit: The quality sensor is typically integrated into the DEF tank header unit. Check the sensor for physical damage, corrosion, and verify the electrical harness for chafed wires or loose pins.

1. 1

   Drain the Tank

   If the DEF fluid tests bad (diluted or contaminated), place a drain pan under the DEF tank and completely drain the fluid.

2. 2

   Flush the System

   Flush the DEF tank with distilled water to remove contaminants and crystallized deposits. Never use tap water or cleaning chemicals.

3. 3

   Remove the DEF Header

   If the fluid was good but the sensor has failed, disconnect the electrical harness and DEF lines from the DEF Head Unit on top of the tank.

4. 4

   Extract the Sensor

   Remove the mounting flange bolts and carefully extract the DEF Head Unit assembly from the tank.

5. 5

   Install the New Part

   Install the new DEF Quality Sensor / Head Unit, ensuring the O-ring/gasket is properly seated to prevent leaks. Reconnect the DEF lines and electrical harness.

6. 6

   Refill

   Refill the tank with fresh, high-quality, ISO 22241-compliant Diesel Exhaust Fluid.

7. 7

   Clear Codes and Validate

   Connect a diagnostic scan tool (like the Case IH Electronic Service Tool) to clear the fault codes. You must then perform an 'Inducement Validation Restart' (a stationary SCR system test) to allow the ECM to verify the new DEF quality and clear the inducement warning.