Case IH 3023 – Engine ECU: Atmospheric Pressure Sensor - Signal Not Plausible Compared with Boost Pressure

The engine control system continuously monitors both the atmospheric (ambient) pressure and the intake manifold boost pressure. When the engine is off or at idle, these two pressure readings should be nearly identical. If the system detects a significant discrepancy between the two sensor signals, it flags the reading as "not plausible" and triggers this fault code.

• Magnum 225
• Magnum 235
• Magnum 250
• Magnum 275
• Magnum 280
• Magnum 310
• Magnum 335
• Magnum 340
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Puma 150
• Puma 165
• Puma 175
• Steiger 280
• Steiger 330
• Steiger 335
• Axial-Flow 5088
• Axial-Flow 6088
• Axial-Flow 7088
• Axial-Flow 5130
• Axial-Flow 7120
• Axial-Flow 7240
• Axial-Flow 8240
• Axial-Flow 9240
• Patriot 4420
• Case 580 Super N
• SR series skid steer loaders
• SV series skid steer loaders

1. 1

   Perform Key-On, Engine-Off (KOEO) data comparison using diagnostic software to compare boost pressure with ambient pressure (difference should be close to zero)

2. 2

   Check the wiring harness and connectors for the boost pressure sensor for any shorts, open circuits, or corrosion

3. 3

   Determine which sensor is reading inaccurately, noting that the atmospheric pressure sensor may be located inside the Engine ECU

1. 1

   Park the machine safely and turn the ignition to the ON position (engine off).

2. 2

   Using a diagnostic tool, monitor the live data for both the Boost Pressure and Atmospheric Pressure to see which sensor is reporting an implausible value.

3. 3

   Inspect the electrical connector and wiring harness leading to the Intake Manifold Air Pressure (Boost) Sensor.

4. 4

   If the boost pressure sensor is deemed faulty, disconnect its wiring harness, remove the retaining hardware, and pull the sensor from the intake manifold.

5. 5

   Install the replacement boost pressure sensor, ensuring you use a new O-ring to prevent boost leaks.

6. 6

   If the diagnostic test proves the boost sensor is fine but the atmospheric pressure sensor is out of range, and your specific machine houses this sensor internally within the ECU, the Engine ECU itself will need to be replaced.

   ECU replacement is sometimes deemed unnecessary if the machine is never run in high-altitude environments where precise atmospheric compensation is critical.

7. 7

   Clear the fault codes using your diagnostic tool and run the engine to verify the repair.