Massey Ferguson 100.03 – Engine Control Unit (ECU): Engine Oil Pressure Sensor High Voltage. (ECU)

The Engine Control Unit (ECU) is receiving a voltage signal from the engine oil pressure sensor that is higher than the acceptable operating range (typically exceeding 4.85V). This condition generally points to an electrical fault rather than a mechanical oil pressure failure. It is most commonly caused by a short circuit to a power source, an open circuit on the sensor's ground wire, or an internally shorted/failed sensor.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Inspect the wiring harness leading to the engine oil pressure sensor for chafing, melting, or physical damage that could cause a short to power.

2. 2

   Disconnect the sensor plug and check for water ingress, corrosion, or bent pins.

3. 3

   Using a multimeter, probe the sensor signal wire with the key ON (engine off). If the voltage is reading above 4.85V, check the ground circuit for continuity to the ECU. An open ground will cause the signal voltage to pull high.

4. 4

   If the wiring harness tests good (proper 5V reference, good ground, and continuity on the signal wire to the ECU), the sensor itself has failed internally and must be replaced.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes during repair.

2. 2

   Locate Sensor

   Locate the engine oil pressure sensor on the engine block (location varies slightly depending on the specific Sisu/AGCO Power engine model).

3. 3

   Remove Sensor

   Depress the locking tab on the electrical connector and unplug it. Use a properly sized deep socket or wrench to unthread the faulty sensor from the engine block. Have a rag ready to catch any residual oil.

4. 4

   Install New Sensor

   Thread the new OEM sensor into the block by hand to prevent cross-threading, then tighten to the manufacturer's specified torque.

5. 5

   Reconnect

   Plug the electrical connector back in until it clicks securely. Reconnect the battery.

6. 6

   Clear Codes

   Use a diagnostic tool to clear the 00100.03 fault code from the ECU.

7. 7

   Verify Repair

   Start the engine and verify that the dashboard oil pressure reading is normal and the fault code does not return.