Massey Ferguson E109.03 – Engine Control Unit (ECU): Coolant Pressure Sensor Signal Voltage High

The measured voltage signal from the coolant pressure sensor is above the normal operating range. The system flags this when it detects an open circuit or a short to a high voltage source in the sensor's circuit.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Inspect the coolant pressure sensor wiring harness for any signs of chafing, breaks, or melting that could cause an open circuit or a short to a power source.

2. 2

   Disconnect the sensor and check the pins for corrosion, moisture, or pushed-back terminals.

3. 3

   Use a multimeter to verify the reference voltage at the connector and check for continuity back to the ECU to rule out a broken wire.

4. 4

   Temporarily connect a known-good coolant pressure sensor to see if the fault code changes from active to inactive. If the code clears, the original sensor has failed internally.

1. 1

   Power Down

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

2. 2

   Relieve Pressure

   Ensure the engine is completely cool before opening the cooling system to prevent burns and relieve any residual system pressure.

3. 3

   Remove the Sensor

   Locate the coolant pressure sensor on the engine cooling circuit. Disconnect the electrical harness. Unthread the faulty sensor from its port.

4. 4

   Install the New Sensor

   Thread the new OEM coolant pressure sensor into the port. Tighten to the manufacturer's specified torque (do not overtighten, as this can damage the brass threads or the housing).

5. 5

   Reconnect

   Plug the electrical connector back into the sensor, ensuring the locking tab clicks into place.

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic service tool (like WinEEM3/4 or an AGCO diagnostic tool) to clear the stored E109.03 fault code from the ECU.

7. 7

   Test Run

   Start the engine, check for coolant leaks around the new sensor, and verify that the fault code does not return.