Case IH F-175-21 - ECU – Engine Control Unit (ECU): Oil temperature too low

The control module is receiving a signal from the Engine Oil Temperature (EOT) sensor that has drifted low or is stuck in a range that is lower than expected for the engine's current operating conditions and load.

• MAGNUM AFS Connect
• Case IH Magnum Series
• Magnum 400 AFS Connect
• Case IH Puma Series
• Puma 200
• Puma 215
• Puma 230

1. 1

   Verify Actual Temperature: Check if the engine is genuinely running cold. A stuck-open oil or coolant thermostat can prevent the engine from reaching operating temperature, triggering this code as a symptom rather than a sensor failure.

2. 2

   Check for Associated Codes: Ensure there are no other active codes for the EOT sensor (such as F-175-00 for voltage too high, or F-175-01 for voltage too low), which would indicate a hard electrical short rather than a drifted signal.

3. 3

   Inspect the Wiring Harness: Inspect the connections at the Engine Oil Temperature (EOT) sensor. Look for frayed wires, corrosion, or loose pins at both the sensor connector and the ECU harness.

4. 4

   Test the Sensor: With the key OFF, disconnect the EOT sensor and measure its resistance with a multimeter. Compare the reading against the OEM temperature/resistance chart. If the resistance is out of specification for the ambient temperature, the sensor has failed.

1. 1

   Prep the Machine

   Park the tractor on a level surface, turn off the engine, and allow it to cool.

2. 2

   Disconnect Power

   Always disconnect the main negative battery cable first to protect the ECU from voltage spikes.

3. 3

   Locate the Sensor

   Locate the Engine Oil Temperature sensor on the engine block (typically near the oil filter housing or main oil gallery).

4. 4

   Remove the Sensor

   Disconnect the electrical harness connector. Clean the area around the sensor to prevent dirt from entering the oil system, then unscrew and remove the faulty EOT sensor.

5. 5

   Install the New Part

   Install the new sensor (ensuring the sealing washer or O-ring is properly seated) and tighten it to the manufacturer's specified torque.

6. 6

   Reassemble

   Reconnect the electrical harness connector and reconnect the negative battery cable.

7. 7

   Clear Codes and Test

   Connect a diagnostic tool (such as the Case IH Electronic Service Tool) to clear the F-175-21 fault code. Start the engine, check for oil leaks around the new sensor, and run the machine up to operating temperature to verify the code does not return.