Case IH 19141 – Engine Control Module (ECM) or UCM (Urea Control Module): DEF/AdBlue Quality Sensor Detected Diesel Fuel

The DEF/AdBlue quality sensor has detected diesel fuel in the DEF/AdBlue tank. This is a critical error because the introduction of diesel fuel into the Selective Catalytic Reduction (SCR) system can cause catastrophic damage to the DEF dosing valve, pump, and the SCR catalyst itself.

• Tier 4b
• 240 Series Axial-Flow Combines
• Quadtrac 500 / Rowtrac Tractors
• Magnum
• Steiger
• Optum
• Puma
• Maxxum

1. 1

   Visually and physically inspect the fluid in the DEF tank for separation, discoloration, or the distinct smell of diesel fuel

2. 2

   Verify with the operator if diesel fuel was accidentally pumped into the DEF tank

3. 3

   Inspect the DEF quality sensor wiring harness and electrical connector for corrosion caused by ammonia gas leaks

4. 4

   Check for concurrent DEF sensor codes (such as 19144 or 19153) that might indicate a total sensor failure rather than actual fluid contamination

1. 1

   Shut Down and Isolate

   Turn off the machine and safely access the DEF tank assembly.

2. 2

   Drain the System

   If diesel fuel contamination is confirmed, completely drain the DEF tank. Do not run the engine, as this will pull the contaminated fluid deeper into the dosing system.

3. 3

   Flush the Tank and Lines

   Thoroughly flush the DEF tank, suction lines, and dosing lines with distilled water or fresh DEF to remove all residual diesel fuel.

4. 4

   Replace the Sensor/Header

   If the sensor has been submerged in diesel fuel, or if the circuit board is corroded, the sensor (often integrated into the DEF Tank Header Unit) must be replaced.

5. 5

   Refill and Prime

   Refill the tank with fresh, certified DEF/AdBlue fluid.

6. 6

   Clear Codes

   Use an AFS Pro display or a dealer diagnostic scan tool to clear the fault codes. Run the engine to allow the system to sample the new fluid and verify that the code does not return.