Case IH 19823 – Engine Control Unit (ECU): Intake manifold temperature is too high.

The Engine Control Unit (ECU) has detected that the signal voltage from the intake manifold temperature sensor is higher than expected (typically greater than 4.93 to 4.94 VDC for at least 0.5 seconds). The ECU determines the temperature has exceeded the safe warning limit, substitutes a default replacement value (e.g., 29.96 °C / 85.93 °F), and initiates an engine derate.

• Tier 4b
• Case IH MX Magnum Tractors
• Case Track Loaders (TR270, TR310, TR320, TR340, TV380)
• Case/CNH STM N Series Loaders

1. 1

   Check system battery voltage to ensure it is at least 10 VDC, as low voltage can cause erratic sensor readings.

2. 2

   Inspect the sensor signal circuit wiring harness for a short circuit to positive or an open circuit.

3. 3

   Check for related fault codes that might indicate a broader electrical issue, such as code 187 (Sensor Supply 2 Voltage is too low) or 19824 (Intake manifold temperature is too low).

4. 4

   Verify sensor plausibility using a diagnostic tool to read live intake manifold temperature data and compare it to ambient temperature when the engine is cold.

1. 1

   Access the Sensor

   Locate the intake manifold temperature sensor on the engine block. Depending on the machine, this may require removing the left and right fan shields, or loosening the air cleaner outlet tube and turbocharger elbow clamps to gain clear access.

2. 2

   Disconnect the Harness

   Carefully disconnect the electrical plug from the intake manifold temperature sensor.

3. 3

   Test the Circuit

   Using a multimeter, probe the harness connector to ensure the ECU is sending the correct 5V reference signal and that the ground is solid.

4. 4

   Replace the Sensor

   If the wiring tests good, the sensor itself has failed internally. Unthread the old sensor from the manifold and install the replacement part.

5. 5

   Clear Codes and Reset Inducement

   Reconnect the harness. Use a diagnostic tool (such as the CNH EST, TEXA, or Cojali) to clear the fault codes.

6. 6

   Derate Unlock

   Perform an 'Inducement Unlock / Counter Reset' via the diagnostic tool once the repair is finished. Restart the engine 3 times to allow the ECU to confirm the system is functioning normally. If not confirmed within 30 minutes of operation, the engine will derate again.