Case IH 19425 – VCM (Vehicle Control Module) / Engine Control Module (ECM): Plausibility temperature monitoring with ambient or catalyst temperatures.

This is a logic/plausibility error where the control module continuously monitors the ambient air temperature and compares it against the exhaust/catalyst temperature sensors. If the temperature delta between these sensors does not make logical sense, the system flags the readings as implausible.

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

1. 1

   Perform a cold soak comparison by letting the machine sit overnight so the engine and exhaust cool completely. Connect a diagnostic scan tool and verify that Ambient Air Temperature, Catalyst Upstream Temperature, and Catalyst Downstream Temperature all read nearly identical to the actual outside weather temperature.

2. 2

   Identify the outlier sensor from the cold soak test; the sensor reading significantly higher or lower than the actual ambient temperature is the failed component.

3. 3

   Inspect the wiring harness and connectors going to the suspect sensor for chafed wires, melted conduit near the exhaust, or corrosion inside the connector pins.

1. 1

   Power Down

   Turn off the machine and turn off the master battery disconnect switch.

2. 2

   Locate the Faulty Sensor

   Based on your diagnostic scan, locate either the Ambient Air Temperature sensor (usually mounted near the front grille/intake) or the Catalyst Temperature Sensor (threaded into the SCR/DOC exhaust canister).

3. 3

   Verify Wiring

   Disconnect the sensor. Use a multimeter to check for a 5V reference signal and a good ground coming from the VCM harness. If the wiring is damaged, repair the harness.

4. 4

   Replace the Sensor

   If the harness tests good, the sensor itself has internally failed or drifted out of calibration. Unthread the faulty exhaust temperature sensor or unclip the ambient temperature sensor and install the replacement.

5. 5

   Clear and Verify

   Reconnect the battery, connect your diagnostic tool, and clear fault code 19425. Start the engine and allow it to reach operating temperature to ensure the DEF/AdBlue system enters closed-loop control and verify the code does not return.