Massey Ferguson E108.04 – Engine Control Unit (ECU) / EEM3 or EEM4: Ambient Pressure Sensor - Voltage below normal (or shorted to low source)

The engine monitoring system has detected a voltage reading from the ambient (barometric) pressure sensor that falls below the normal operational range. The sensor is an internal hardware component built directly into the ECU circuit board.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 7617
• 7600 Dyna-4
• 7600 Dyna-6
• 7600 Dyna-VT
• 8600 Series

1. 1

   Connect a diagnostic tool (e.g., WinEEM3/WinEEM4 Service Tool) and save the current error log.

2. 2

   Erase the error log and restart the ECU/engine.

3. 3

   Check if the fault code E108.04 (SPN 108 FMI 4) returns as an active fault.

4. 4

   If the fault remains active, verify the issue by temporarily connecting a known-good replacement ECU.

5. 5

   If the system functions normally and the fault is not active with the test ECU, the original ECU has a confirmed hardware defect.

1. 1

   Disconnect Power

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

2. 2

   Remove the ECU

   Locate the Engine Control Unit (usually mounted on the side of the engine block or firewall, depending on the model). Disconnect the main wiring harness connectors and unbolt the module.

3. 3

   Replace the ECU

   Because the ambient pressure sensor is integrated into the ECU's internal circuitry, it cannot be replaced or repaired individually. The entire ECU must be replaced.

4. 4

   Install and Program

   Install the new ECU. A dealer or qualified technician must flash/program the new ECU with the correct software parameters for your specific tractor model and engine serial number.

5. 5

   Clear Codes

   Reconnect the battery, turn the key on, and use the diagnostic tool to clear any residual codes and verify that E108.04 has not returned.