Case IH 19131 – Engine Control Module (ECM) or Dosing Control Unit (DCU) / Aftertreatment Control Module (ACM): DEF/AdBlue Quality Error

This code is triggered when the DEF quality sensor detects that the urea concentration in the Diesel Exhaust Fluid is outside the acceptable specification (which should be 32.5%), or if the sensor detects an anomaly such as air or diesel in the fluid. It can also indicate an internal failure of the DEF quality sensor itself, which is a common issue caused by ammonia gas corroding the sensor's internal circuit board.

• Tier 4b
• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 225
• Magnum 275
• Magnum 340
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 135
• Maxxum 140
• Maxxum 145
• Puma 115
• Puma 125
• Puma 130
• Puma 140
• Puma 145
• Puma 150
• Puma 155
• Puma 160
• Puma 165
• Puma 170
• Puma 180
• Puma 185
• Puma 195
• Puma 200
• Puma 210
• Puma 215
• Puma 225
• Puma 230
• Steiger 500
• Combine 7230
• Combine 8240

1. 1

   Test the DEF Fluid: Use a DEF refractometer to test the fluid in the tank. It must read exactly 32.5% urea concentration. If it is diluted with water or degraded from age/heat, the fluid is the problem, not the sensor.

2. 2

   Inspect for Contamination: Check the DEF tank for signs of diesel fuel, dirt, or heavy crystallization.

3. 3

   Check Wiring and Connections: Inspect the electrical connector at the DEF header (top of the DEF tank) for corrosion, oxidation, or backed-out pins.

4. 4

   Verify Voltage: Check for proper voltage and continuity between the ECM/DCU and the DEF quality sensor to rule out a wiring harness failure.

1. 1

   Drain and Flush (If fluid is bad)

   If the DEF is contaminated or degraded, drain the DEF tank completely. Flush the tank with distilled water or fresh DEF, then refill with new fluid. If the code clears, the sensor is fine.

2. 2

   Clean the Area

   If the fluid is good but the sensor has failed, you must replace the DEF header unit (the quality sensor is integrated into this unit). Thoroughly clean the top of the DEF tank around the header to prevent dirt from falling into the tank during removal.

3. 3

   Disconnect Lines

   Disconnect the electrical connector and the DEF supply/return lines from the top of the DEF header.

4. 4

   Remove the Header

   Unscrew the locking ring or remove the mounting bolts securing the DEF header to the tank.

5. 5

   Extract the Sensor

   Carefully pull the old DEF header/sensor assembly straight up and out of the tank.

6. 6

   Install the New Part

   Insert the new DEF quality sensor assembly into the tank. Ensure the gasket/O-ring is properly seated and secure the locking ring or bolts.

7. 7

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical connector.

8. 8

   Refill and Reset

   Refill the tank with fresh DEF. Use a dealer diagnostic tool (EST) to clear the 19131 fault code and run an SCR system test to reset the emissions memory.