Case IH 19165 – Engine Control Module (ECM / ECU): DEF/AdBlue quality sensor internal failure (Temperature sensor circuit short to battery)

The Engine Control Unit (ECU) has detected a voltage on the temperature sensor circuit that is shorted to the battery. This is typically caused by an internal failure of the sensor's circuit board or a wiring harness short.

• Tier 4b
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240
• Magnum
• Steiger
• Quadtrac
• Farmall
• Maxxum
• Puma

1. 1

   Inspect the wiring harness and connector leading to the DEF quality sensor for chafing, corrosion, or exposed wires that could be shorting to battery voltage.

2. 2

   Test for internal vs. external short: Disconnect the sensor and use a multimeter to check the harness side for a short to battery power. Do not probe the ECU connector directly.

3. 3

   Check for ammonia corrosion: Inspect if ammonia gas from the DEF fluid has seeped into the top of the sensor housing and corroded the internal circuit board.

4. 4

   Check for software updates: Contact a dealer to see if your machine is eligible for a software flash that eliminates the requirement for the DEF quality sensor before buying hard parts.

1. 1

   Turn off the machine, disconnect the battery, and locate the DEF tank.

2. 2

   Thoroughly clean the area around the top of the DEF tank and the header unit flange to prevent dirt from falling into the DEF fluid.

3. 3

   Disconnect the electrical connector from the DEF quality sensor.

4. 4

   Disconnect the DEF supply and return lines from the header unit.

5. 5

   Unbolt or unthread the mounting flange/seal that secures the DEF header unit to the tank.

6. 6

   Carefully pull the old DEF header unit assembly out of the tank.

7. 7

   Install the new DEF quality sensor/header unit, ensuring you use a new seal/O-ring to prevent leaks and gas seepage.

8. 8

   Reconnect the DEF fluid lines and the electrical connector.

9. 9

   Reconnect the battery and use a diagnostic scan tool to clear the fault codes.