Case IH 3457 (F-105-03) – Engine Control Unit (ECU) / Engine Control Module (ECM): Intake manifold temperature sensor voltage is higher than expected.

The FMI 03 designation specifically means 'Voltage Above Normal' or 'Shorted to high source.' The engine's control system monitors the signal circuit from the intake manifold temperature sensor. If the system determines that the signal circuit voltage is greater than the normal operating threshold (typically >4.94 Volts), it triggers this fault. This condition is almost always caused by an open circuit (such as a disconnected or broken wire) or a sensor that has failed internally, causing the voltage to float to the 5V reference maximum.

• VESTRUM CVX
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• 2377
• 2388
• 2577
• 2588
• Farmall series (40, 45, 50, 115U)
• Magnum series (MX Magnum, 215, 255, 305, 335)
• Maxxum
• MXM
• MXU
• 8800 Series Sugar Cane Harvesters

1. 1

   Visually inspect the intake manifold temperature sensor and electrical plug for a disconnected harness, broken wires, severe corrosion, or pushed-out pins.

2. 2

   Perform a voltage check by disconnecting the sensor plug, turning the key ON, and verifying the ECU supplies a 5V reference signal and a solid ground.

3. 3

   Test the wiring harness signal wire for continuity between the sensor connector and the ECU connector, ensuring it is not shorted to the 5V supply or battery voltage.

4. 4

   Verify sensor condition; if wiring, 5V reference, and ground are intact, the sensor likely has an internal open-circuit failure.

1. 1

   Turn off the machine and disconnect the battery ground to protect the ECU.

   Turn off the machine and disconnect the battery ground to protect the ECU.

2. 2

   Gain access to the intake manifold temperature sensor.

   Depending on the model (e.g., MX series tractors), this may require removing the left/right fan shields or loosening the air cleaner outlet tube at the turbocharger elbow.

3. 3

   Depress the locking tab and disconnect the electrical plug from the sensor.

   Depress the locking tab and disconnect the electrical plug from the sensor.

4. 4

   If wiring damage was found during diagnostics, repair the harness using approved weather-sealed connectors.

   If wiring damage was found during diagnostics, repair the harness using approved weather-sealed connectors.

5. 5

   If replacing the sensor, unscrew the faulty sensor from the intake manifold.

   If replacing the sensor, unscrew the faulty sensor from the intake manifold.

6. 6

   Install the new sensor and tighten it to the manufacturer's specified torque.

   Install the new sensor and tighten it to the manufacturer's specified torque.

7. 7

   Reconnect the electrical plug, ensuring the weather seal is intact and the locking tab clicks securely into place.

   Reconnect the electrical plug, ensuring the weather seal is intact and the locking tab clicks securely into place.

8. 8

   Reconnect the battery, turn the key ON, and use the machine's diagnostic display or a service tool to clear the inactive fault code.

   Reconnect the battery, turn the key ON, and use the machine's diagnostic display or a service tool to clear the inactive fault code.

9. 9

   Start the engine and verify that the code does not return and that the engine is no longer derating fuel flow.

   Start the engine and verify that the code does not return and that the engine is no longer derating fuel flow.