Case IH 3446 (DTC F6A2) - ECU – Engine Control Unit (ECU): Torque limitation due to excessive intake air temperature

This code is logged when the Engine Control Unit detects that the intake air temperature is excessively high for a duration longer than 50.0 milliseconds. To protect the engine from damage, the system automatically limits engine torque (power reduction).

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• Puma series
• Magnum series (MX210, MX230, MX255, MX285)
• Steiger models

1. 1

   Check the failure memory for other active fault codes influencing the air intake temperature (such as sensor voltage errors or cooling system faults)

2. 2

   Physically inspect the charge air cooler (intercooler) and radiator for debris, chaff, or dirt that could be restricting airflow

1. 1

   Scan for Codes

   Connect your diagnostic tool and pull all active and stored codes from the ECU. Look specifically for MAP/IAT sensor voltage codes or coolant temperature codes.

2. 2

   Address Primary Faults

   If other codes are present (e.g., sensor short to ground, voltage higher/lower than expected), diagnose and repair those electrical issues first, as they are likely triggering the 3446 (F6A2) torque limitation.

3. 3

   Inspect Airflow & Cooling

   If no other codes are present, thoroughly clean the exterior of the charge air cooler and radiator. Ensure the engine cooling fan is operating correctly.

4. 4

   Live Data Monitoring

   Use the diagnostic tool to monitor the live data for the Intake Air Temperature. If the temperature reading is erratic, stuck at a default high value, or out of calibration compared to ambient temperature when the engine is cold, the sensor or its wiring is faulty.

5. 5

   Wiring Check

   Inspect the wiring harness and connector at the Intake Manifold Temperature and Pressure Sensor for chafing, corrosion, or loose pins.

6. 6

   Replace Sensor

   If the wiring is intact but the sensor provides false high-temperature readings, replace the MAP/IAT sensor.

7. 7

   Clear and Test

   Clear the fault codes and run the machine under load to verify that the intake air temperature remains within normal limits and the torque limitation does not return.