Case IH F-105-00 - ECU – ECU: Intake manifold temperature sensor voltage is higher than expected

This fault indicates an electrical issue within the intake manifold temperature sensor's signal circuit. The Engine Control Unit (ECU) continuously monitors the voltage returning from this sensor. If the ECU detects that the signal circuit voltage is abnormally high (typically greater than 4.94 Volts), it triggers this fault. A 'voltage higher than expected' condition almost always points to an open circuit, a short to a high-voltage source, or a completely failed sensor internally.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines
• 2388
• 2377
• 2577
• 2588
• Farmall 95U
• Farmall 105U
• Farmall 115U
• Farmall 105A
• Maxxum series
• MXM
• MXU
• Magnum MX255
• Magnum MX270
• Magnum MX285

1. 1

   Visual Inspection: Locate the sensor on the intake manifold. Inspect the sensor connector for pushed-out pins, corrosion, or moisture.

2. 2

   Wiring Harness Check: Trace the wiring harness back to the ECU. Look for chafed wires that might be shorting to power or severed wires causing an open circuit.

3. 3

   Voltage Test: Disconnect the sensor and use a multimeter to check the voltage at the signal wire terminal on the harness side (key ON, engine OFF). If the ECU is reading > 4.94V, verify if the ground circuit is open.

4. 4

   Physical Blockage Check: Ensure the charge air cooler (intercooler) and rotary screens are blown out and free of chaff/dirt, as extreme heat soak can sometimes damage sensors.

1. 1

   Power Down

   Turn off the machine, remove the key, and allow the engine to cool completely.

2. 2

   Locate the Sensor

   The sensor is typically mounted at the top of the intake manifold or near the charge air cooler outlet.

3. 3

   Disconnect

   Depress the locking tab on the electrical pigtail and disconnect the harness from the sensor.

4. 4

   Remove the Sensor

   Using a deep socket or wrench, carefully unthread the faulty sensor from the intake manifold.

5. 5

   Install the New Sensor

   Thread the new OEM sensor into the manifold. Tighten to the specified torque (do not over-tighten, as the manifold threads or sensor housing can crack).

6. 6

   Reconnect

   Plug the electrical harness back into the sensor until it clicks securely.

7. 7

   Clear Codes

   Turn the key to the ON position and use your diagnostic tool (or the machine's onboard diagnostic display) to clear the inactive fault codes.