Case IH 19201 – VCM (Vehicle Control Module) / Engine ECU: Plausibility check error of the fifth fresh air temperature sensor at cold start

When the machine is started cold (after sitting long enough for all engine components to equalize to ambient temperature), the Vehicle Control Module (VCM) compares the readings of various temperature sensors. The reading from the fifth fresh air temperature sensor is implausible—meaning it is reading significantly higher or lower than the ambient temperature or the other temperature sensors (such as coolant or oil temperature).

• Tier 4b
• Case 580N
• Case 580SN
• Case 580SN WT
• Case 590SN

1. 1

   Connect a diagnostic scan tool and view the live data for all temperature sensors (coolant, oil, intake air, and fresh air) before starting a cold engine. All sensors should read within a few degrees of ambient outside temperature. Identify the specific sensor reading out of range.

2. 2

   Inspect the wiring harness and the electrical connector going to the fresh air temperature sensor for chafed wires, corrosion, or pushed-out pins.

3. 3

   Disconnect the sensor and test the wiring continuity from the sensor connector back to the VCM pins to rule out an open or short circuit in the harness.

1. 1

   Turn off the machine, remove the key, and disconnect the battery ground strap to prevent electrical shorts.

   Turn off the machine, remove the key, and disconnect the battery ground strap to prevent electrical shorts.

2. 2

   Locate the faulty fresh air temperature sensor on the engine intake/air filter housing assembly.

   Locate the faulty fresh air temperature sensor on the engine intake/air filter housing assembly.

3. 3

   Disconnect the electrical connector from the sensor.

   Disconnect the electrical connector from the sensor.

4. 4

   If the diagnostic checks revealed a wiring issue, repair the damaged section of the harness or replace the pigtail connector.

   If the diagnostic checks revealed a wiring issue, repair the damaged section of the harness or replace the pigtail connector.

5. 5

   If the wiring is intact, the sensor itself has failed internally. Unthread and remove the faulty temperature sensor.

   If the wiring is intact, the sensor itself has failed internally. Unthread and remove the faulty temperature sensor.

6. 6

   Install the new replacement temperature sensor and tighten it to the manufacturer's specified torque.

   Install the new replacement temperature sensor and tighten it to the manufacturer's specified torque.

7. 7

   Reconnect the electrical connector, ensuring the locking tab clicks into place.

   Reconnect the electrical connector, ensuring the locking tab clicks into place.

8. 8

   Reconnect the battery ground strap.

   Reconnect the battery ground strap.

9. 9

   Use a diagnostic scan tool to clear the inactive 19201 fault code.

   Use a diagnostic scan tool to clear the inactive 19201 fault code.

10. 10

    Perform a cold start to verify that the sensor reads ambient temperature correctly and the code does not return.

    Perform a cold start to verify that the sensor reads ambient temperature correctly and the code does not return.