Case IH F-519044-12 - ECU – Engine Control Unit (ECU): DEF/AdBlue Quality Sensor Internal Failure (Temperature sensor failure)

The DEF (Diesel Exhaust Fluid) quality sensor is reporting a self-diagnostic error specifically related to its internal temperature signal. The sensor is responsible for measuring both the urea concentration and the temperature of the DEF fluid. When the temperature value is implausible, out of range, or the sensor detects an internal circuit failure, this code is triggered.

• MAGNUM AFS Connect
• 240 Series Combines
• 7240
• 8240
• 9240
• 9230
• Magnum
• Steiger
• Puma
• Maxxum

1. 1

   Inspect the top of the DEF header for signs of ammonia gas leakage, which is a known issue that corrodes the internal circuit boards of these sensors.

2. 2

   Inspect the wiring harness connecting to the DEF quality sensor for short circuits, open wires, or corrosion at the connector.

3. 3

   Ensure the DEF tank has not been contaminated with diesel fuel or water, which can cause erratic sensor readings.

4. 4

   Use a diagnostic scan tool to clear the memory. If an engine derate/performance limiter is active, disable it with the tester and run the machine above 1600 RPM to see if the code returns.

1. 1

   Preparation

   Turn off the machine and disconnect the battery. Clean the area around the top of the DEF tank to prevent dirt from falling into the tank.

2. 2

   Disconnect Lines

   Carefully disconnect the electrical harness connector from the DEF header.

3. 3

   Disconnect Coolant/Fluid Lines

   Disconnect the DEF supply/return lines and the engine coolant lines (which run through the header to thaw frozen DEF). *Note: Be prepared for minor coolant and DEF spillage.*

4. 4

   Remove the Header

   Remove the mounting bolts or the retaining ring securing the DEF header flange to the top of the DEF tank. Carefully pull the header assembly (which includes the suction tube, heater coil, and quality/temperature sensor) out of the tank.

5. 5

   Install the New Unit

   Insert the new DEF header/sensor assembly into the tank. Always use a new O-ring/gasket to ensure a proper seal.

6. 6

   Reassembly

   Reconnect the DEF lines, coolant lines, and electrical connectors.

7. 7

   System Reset

   Reconnect the battery. Use a diagnostic tool to clear the F-519044-12 fault code and perform an SCR system reset or Urea-Dosing-System-Test (UDST) to verify the repair.