Case IH 3446 (F-519871-31) - ECU – Engine Control Module (ECM) / Engine ECU: Torque limitation due to excessive intake air temperature.

This condition occurs when the sensor monitoring the air entering the engine detects that the intake air temperature has exceeded the safe operational threshold. To protect the engine components and the turbocharger from thermal damage, the system automatically limits the engine's torque (power output).

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• Farmall series (40, 45, 50, 115U)
• Magnum series (225, 250, 285, 310)
• Steiger / STX 4WD Tractors
• 8800 Series Sugar Cane Harvesters

1. 1

   Inspect the Charge Air Cooler (Air-to-Air Cooler) and radiator exterior fins for blockages caused by dirt, chaff, or debris

2. 2

   Verify the engine cooling fan is engaging properly to pull air through the coolers

3. 3

   Inspect the wiring harness and connectors leading to the Intake Air Temperature (IAT) / Intake Manifold Temperature (IMT) sensor for chafing, shorts to ground, or corroded pins

4. 4

   Test sensor output using a diagnostic tool to monitor live data for the intake manifold temperature. If it reads impossibly high (e.g., 150°F+ when cold), the sensor is likely shorted or out of calibration

1. 1

   Access the Sensor

   Locate the intake manifold temperature sensor on the engine's intake manifold piping.

2. 2

   Clear Obstructions

   Depending on the model (e.g., MX285), you may need to remove harness/hose retainers or fan shields to gain clear access to the sensor.

3. 3

   Disconnect

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

4. 4

   Remove

   Unscrew the faulty sensor from the intake manifold.

5. 5

   Install

   Thread the new sensor into the manifold and tighten to the OEM torque specification.

6. 6

   Reconnect

   Plug the electrical harness back into the new sensor, ensuring the locking tab clicks into place.

7. 7

   Reassemble & Clear

   Reinstall any shields or retainers that were removed. Use a diagnostic tool to clear the 3446 fault code from the ECM, then test-run the machine under load to ensure full power is restored.