Case IH PD – Engine Control Unit (ECU): Ambient Pressure Sensor (PHY), Data Incorrect

The engine monitoring system has detected that the signal from the ambient (barometric) pressure sensor is erratic, intermittent, not plausible, or outside the expected threshold limits. Engine functions dependent on the ambient pressure sensor (like altitude compensation) are disabled.

• MXM
• MXM Series
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum Series
• Steiger
• Puma
• CVX
• AFX Series
• AFX8010
• 8800 Series Sugar Cane Harvesters

1. 1

   Determine if your specific engine utilizes an internal (built into the ECU) or external ambient pressure sensor

2. 2

   For external sensors: Inspect the wiring harness and check the 5V DC reference supply to the sensor. Look for open circuits, shorts to ground, or shorts to a high voltage source

3. 3

   For internal sensors: Test the machine with a known-good replacement ECU to verify if the original ECU's internal hardware is defective

4. 4

   Perform a plausibility check to verify if the sensor reading is stuck above the maximum range or below the minimum range (Note: if the machine is never run at high altitudes, replacing an ECU for an internal sensor failure may not be strictly necessary for basic operation)

1. 1

   Turn off machine and disconnect battery

   For External Sensors: Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate sensor

   For External Sensors: Locate the ambient pressure sensor on the engine harness.

3. 3

   Disconnect connector

   For External Sensors: Disconnect the connector: Slide the locking tab (L1) to the right, press down on the release lock (L2), and pull the connector toward you. (If it is stuck, gently use a small screwdriver to float the locking tab).

4. 4

   Replace sensor

   For External Sensors: Unbolt/unthread the defective sensor and install the replacement part.

5. 5

   Reconnect harness

   For External Sensors: Reconnect the wiring harness, ensuring the locking tab clicks securely into place.

6. 6

   Clear fault codes

   For External Sensors: Reconnect the battery, turn the key to the 'ON' position, and clear the fault codes using the H-Menu or a diagnostic service tool.

7. 7

   Disconnect battery

   For Internal Sensors (EEM3 / EEM4 Controllers): Disconnect the battery.

8. 8

   Disconnect ECU harnesses

   For Internal Sensors: Disconnect the main wiring harness blocks from the Engine ECU.

9. 9

   Remove ECU

   For Internal Sensors: Unbolt and remove the defective Engine ECU.

10. 10

    Install new ECU

    For Internal Sensors: Install the new Engine ECU and reconnect the harnesses.

11. 11

    Program ECU

    For Internal Sensors: The new ECU will require dealer-level programming/calibration to flash the correct software for your specific tractor or combine model.