Case IH 3015 (F-174-03) – Engine Control Unit (ECU / ECM): Fuel temperature sensor voltage is higher than expected

The FMI 03 designation indicates "Voltage Above Normal" or "Shorted to high source." The control module monitors the fuel temperature sensor signal circuit. If it detects a voltage greater than 4.93 V in the signal circuit, this fault is logged. When this fault is active, the system may freeze the fuel temperature reading to a default value (e.g., 39.96 °C / 103.93 °F) to protect the engine.

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• Austoft 9900 Sugarcane Harvesters
• Farmall 40, 45, and 50 Tractors

1. 1

   Verify the fault code is active using the Electronic Service Tool (EST).

2. 2

   Inspect the fuel temperature sensor, wiring harness, and ECU connectors for damaged, bent, or displaced pins, corroded terminals, or broken wires. Ensure all connectors are fully seated.

3. 3

   Perform a wiggle test by flexing the involved wiring harnesses while observing the monitor or EST to reveal any intermittent breaks or shorts in the wiring.

4. 4

   Check the sensor signal circuit for a short to battery voltage (ignition power).

1. 1

   Turn off the machine and disconnect the battery ground if performing harness repairs.

2. 2

   Disconnect the connector at the fuel temperature sensor.

3. 3

   Using a multimeter, check the signal wire at the harness connector for voltage with the key ON.

4. 4

   If battery voltage is present on the signal wire, trace the harness back to the ECU, locate the shorted conductor, and repair the damaged wire.

   This indicates a short circuit to the ignition battery power in the harness.

5. 5

   If the wiring harness tests normal (no short to high source and no open circuits), the fuel temperature sensor itself has likely failed internally and is shorting the reference voltage.

6. 6

   Remove the faulty fuel temperature sensor and install the replacement part.

7. 7

   Reconnect the sensor and battery.

8. 8

   Clear the fault code using the EST or monitor. Operate the machine and verify that the monitor indicates normal readings and the code does not return.