Deutz-Fahr 175 – Engine ECU: Oil Temperature Sensor Circuit Fault

The Engine Control Unit (ECU) has detected that the voltage signal from the oil temperature sensor is outside of its expected range. This indicates a cable break (open circuit), a short circuit to ground, or a short circuit to positive in the sensor's wiring circuit. When this fault is active, the system cannot effectively monitor engine oil temperature, which may cause the ECU to default to a substitute temperature value, illuminate a dashboard warning lamp, and reduce engine power to prevent potential damage.

• BFM1013
• BFM2012
• TCD 3.6
• TCD2012
• TCD2013

1. 1

   Visually inspect the wiring harness leading to the oil temperature sensor for chafing, cuts, melting, or corrosion.

2. 2

   Disconnect and inspect the electrical connectors at both the oil temperature sensor and the ECU for bent, corroded, or pushed-out pins.

3. 3

   Perform a continuity check on the signal and ground wires between the sensor and ECU connectors to check for an open circuit (cable break).

4. 4

   Check for a short to ground by measuring resistance between the signal wire and the engine block.

5. 5

   Check for a short to positive by measuring voltage on the disconnected signal wire with the ignition on.

6. 6

   Test the oil temperature sensor resistance. A typical NTC sensor reads approximately 2.5 kΩ at 20°C (68°F). Infinite or near-zero resistance indicates a faulty sensor.

1. 1

   Isolate the fault

   Perform the recommended diagnostic checks to determine whether the fault lies in the wiring harness or the sensor itself.

2. 2

   Repair wiring harness

   If a cable break or short circuit is found, repair the affected wire and seal it against moisture and vibration. Replace the harness section if damage is extensive.

3. 3

   Replace oil temperature sensor

   If the sensor tests faulty, drain the engine oil (or prepare for spillage), unscrew the old sensor, and install the new one to the correct torque specification. Reconnect the harness.

4. 4

   Clear fault codes

   Reconnect the battery and use a diagnostic tool to clear the fault codes from the ECU memory.

5. 5

   Verify repair

   Start the engine and let it reach operating temperature. Monitor the oil temperature reading with a diagnostic tool to confirm it is plausible and the fault code does not return.