Case IH 19169 – Engine Control Module (ECM) or SCR/DEF dosing control module: DEF/AdBlue quality sensor internal failure (Temperature sensor failure)

The DEF quality sensor's internal temperature measuring circuit fails, drifts out of calibration, or experiences an electrical short/open circuit. This is commonly caused by ammonia gas from the DEF permeating the sensor housing and corroding the internal circuit board.

• Tier 4b
• Tier 4B (Final) emissions systems
• 240 Series Axial-Flow Combines
• Steiger/Quadtrac (e.g., 500 Rowtrac)
• Magnum
• Puma
• Maxxum series
• WD1504 Windrowers
• Titan Floaters

1. 1

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

2. 2

   Ensure the DEF tank contains uncontaminated DEF, as water or diesel can cause erratic sensor readings.

3. 3

   Perform a bypass/simulator test using a known-good test sensor or WEMA simulator tool to verify if the diagnostic tool reads correctly (84-88 degrees).

4. 4

   Check with a Case IH dealer for an ECM software update that might eliminate the requirement for the DEF quality sensor.

1. 1

   Preparation

   Turn off the machine, disconnect the battery, and thoroughly clean the top of the DEF tank around the header assembly to prevent dirt from falling into the tank.

2. 2

   Disconnect Electrical

   Unplug the electrical connector from the DEF quality sensor/sending unit.

3. 3

   Disconnect Lines

   Carefully disconnect the DEF suction line, DEF return line, and the engine coolant lines (which run through the header to heat the DEF).

4. 4

   Remove the Header

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

5. 5

   Extraction

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

6. 6

   Installation

   Insert the new DEF header assembly into the tank, ensuring the gasket/O-ring is properly seated. Tighten the locking ring or bolts.

7. 7

   Reconnection

   Reconnect the coolant lines, DEF fluid lines, and the electrical connector.

8. 8

   Finalize

   Reconnect the battery, turn the key on, and use a diagnostic scan tool (like the AFS Pro display or EST) to clear the stored 19169 fault code.