Case IH 17683 (F-519044-31) - ECU – Engine Control Module (ECM): DEF/AdBlue quality sensor failure - quality signal measurement error

The Engine Control Module has detected an internal failure or an implausible measurement signal from the DEF (Diesel Exhaust Fluid) quality sensor. The sensor is sending an erratic or unreadable signal to the computer, preventing the Selective Catalytic Reduction (SCR) system from verifying that the emissions system is functioning correctly.

• VESTRUM CVX
• Farmall 40
• Farmall 45
• Farmall 50
• Austoft 9900
• TR340
• SV340B

1. 1

   Test the DEF fluid using a refractometer to verify the fluid concentration is exactly 32.5% urea. Inadequate quality fuel, water dilution, or contamination can cause chemical reactions that interfere with the sensor's reading.

2. 2

   Inspect the electrical connector at the DEF head unit for corrosion, moisture, or backed-out pins.

3. 3

   Check for accompanying codes such as 17681 (quality signal shorted to battery) or 17682 (quality signal shorted to ground). If those codes are present, the issue is likely in the wiring harness. If 17683 is the only code, the internal measurement mechanism of the sensor has likely failed.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the negative battery cable.

2. 2

   Clean work area

   Locate the DEF tank and thoroughly clean the area around the DEF head unit to prevent dirt from falling into the tank during removal.

3. 3

   Disconnect electrical connector

   Disconnect the electrical harness connector from the DEF head unit.

4. 4

   Disconnect fluid lines

   Relieve any residual pressure and disconnect the DEF suction and return fluid lines from the top of the unit.

5. 5

   Remove mounting hardware

   Remove the mounting bolts or retaining ring securing the DEF head unit to the tank.

6. 6

   Remove DEF head unit

   Carefully pull the DEF head unit straight up and out of the tank.

7. 7

   Flush DEF tank

   If the old sensor failed due to contamination, drain and flush the DEF tank completely before installing the new part.

8. 8

   Insert new DEF head unit

   Insert the new DEF head unit/quality sensor assembly into the tank, ensuring the rubber O-ring/gasket is properly seated to prevent leaks.

9. 9

   Secure and reconnect

   Secure the mounting hardware, reconnect the fluid lines, and plug in the electrical connector.

10. 10

    Refill DEF tank

    Refill the tank with fresh, high-quality DEF.

11. 11

    Clear codes and reset

    Reconnect the battery and use a CNH diagnostic scan tool to clear fault code 17683 and reset the SCR system monitors.