Massey Ferguson 108.04 – Engine ECU: Ambient Pressure Sensor Issue (ECU)

Sensor voltage is below normal or short-circuited to ground. The controller is receiving a signal from the ambient (barometric) pressure sensor that is lower than the acceptable operating range, preventing the engine from properly adjusting the air-to-fuel ratio for the current altitude and atmospheric conditions.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 8600 Series

1. 1

   Visually inspect the ambient pressure sensor, wiring harness, and connector for chafing, melted insulation, or exposed wires

2. 2

   Disconnect the sensor and check the pins for corrosion, moisture, or bent terminals

3. 3

   Turn the ignition ON (engine off) and check the reference voltage pin at the sensor connector for a steady 5V DC supply from the ECU

4. 4

   Test the signal wire for continuity to ground to rule out a short circuit pulling the voltage down

5. 5

   Connect the AGCO EDT (Electronic Diagnostic Tool) to monitor live ambient pressure sensor data; a static, implausible value indicates a dead sensor

1. 1

   Power Down

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

2. 2

   Access the Sensor

   Locate the ambient pressure sensor on the engine block/intake area.

3. 3

   Disconnect

   Depress the locking tab on the electrical connector and pull it straight back to unplug it.

4. 4

   Remove Sensor

   Unbolt or unthread the faulty sensor from its mounting point.

5. 5

   Install New Sensor

   Mount the new sensor. If it is a threaded sensor, ensure the O-ring is seated properly and torque it to the manufacturer's specification (do not overtighten, as these are often plastic-bodied).

6. 6

   Reconnect

   Plug the electrical connector back in until the locking tab clicks.

7. 7

   Clear Codes

   Reconnect the battery. Turn the ignition on and use the EDT diagnostic tool (or the tractor's dash diagnostic menu, if equipped) to clear the inactive 000108.04 fault code.

8. 8

   Test Run

   Start the engine and verify that the check engine light remains off and the code does not return.