Case IH 19202 – Engine Control Module (ECM) or Vehicle Control Module (VCM): Error in case of more than one not plausible fresh air temperature at cold start

When the machine is started cold, the control module compares the readings from various temperature sensors. If multiple sensors report readings that conflict with each other or are mathematically impossible given the conditions, the system flags a plausibility error.

• Tier 4b
• Case N-Series Tractor Loader Backhoes (TLBs)
• Case IH tractors utilizing the MTA CCM & APH Stage V architecture

1. 1

   Perform a cold soak comparison by letting the machine sit overnight or until the engine completely cools to ambient temperature without starting.

2. 2

   Connect the CNH Electronic Service Tool (EST) or a compatible diagnostic scanner to log sensor data.

3. 3

   Compare live data values for all temperature sensors (Fresh Air, Engine Coolant, Intake Manifold); they should be nearly identical to outside ambient air temperature.

4. 4

   Identify the outlier sensor(s) reporting skewed, erratic, or default values (e.g., -40°C or extremely high).

5. 5

   Perform circuit testing on the suspect sensor by disconnecting it and checking the wiring harness for open circuits, short circuits to ground or battery voltage, and inspecting connector pins for corrosion.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground if you are repairing wiring.

2. 2

   Access the Sensor

   Locate the specific temperature sensor that failed the cold soak plausibility test (e.g., the fresh air temperature sensor located near the air intake/filter housing).

3. 3

   Inspect and Clean

   Disconnect the sensor pigtail. Clean the connector with electrical contact cleaner and verify the pins are intact.

4. 4

   Test Resistance

   Measure the resistance across the sensor's terminals with a multimeter and compare it to the OEM specification for the current ambient temperature.

5. 5

   Replace or Repair

   If the sensor's resistance is out of specification (open or shorted internally), replace the sensor. If the sensor tests good, trace the wiring harness back to the ECM/VCM to repair the broken or shorted wire.

6. 6

   Reassemble and Clear Codes

   Reconnect the sensor, reconnect the battery, and use the diagnostic tool to clear the 19202 fault code.

7. 7

   Verify

   Turn the key on (engine off) and verify that the replaced sensor now reads the correct ambient temperature.