Case IH F-175-00 - ECU – Engine Control Unit (ECU): Oil temperature sensor voltage is higher than expected.

The control module is receiving a voltage signal from the oil temperature sensor that exceeds the maximum normal operating threshold. This typically points to an open circuit, a disconnected sensor, a broken ground wire, or a short to a high-voltage source.

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1. 1

   Inspect the engine oil temperature sensor, its connector, and the relevant wiring harnesses for physical damage, bent or dislocated pins, corroded terminals, or broken wires.

2. 2

   Verify that the sensor connector is fully seated and locked into place.

3. 3

   Flex and wiggle the involved wiring harnesses while monitoring the sensor voltage on a diagnostic tool to reveal any intermittent open circuits or shorts.

4. 4

   Check the ECU for the appropriate software version (e.g., A-095) and re-flash or update the software if a known bug applies to your specific machine.

5. 5

   Use a multimeter to check for continuity on the ground circuit and ensure the 5V reference signal is present. If the voltage at the ECU pin is high but the wiring is intact, the sensor itself has failed open.

1. 1

   Safety First

   Turn off the machine, engage the parking brake, and disconnect the negative battery terminal to prevent electrical shorts during repair.

2. 2

   Locate the Sensor

   Locate the engine oil temperature sensor on the engine block (location varies slightly depending on engine displacement, but it is typically near the oil filter housing or main oil gallery).

3. 3

   Disconnect

   Unplug the wiring harness connector from the sensor.

4. 4

   Remove the Sensor

   Place a catch pan underneath the sensor area to catch any residual oil. Use a deep socket or wrench to carefully unthread and remove the faulty oil temperature sensor.

5. 5

   Install the New Sensor

   Thread the new OEM sensor into the port. Tighten to the specific torque rating outlined in your engine's service manual to avoid cracking the housing.

6. 6

   Reconnect

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

7. 7

   Clear Codes

   Reconnect the battery. Turn the key to the ON position and use a CNH Electronic Service Tool (EST) or compatible scanner to clear the F-175-00 fault code.

8. 8

   Test

   Start the engine and monitor the oil temperature reading on the dash or diagnostic tool to verify it is reading accurately and the code does not return.