Case IH 3794 (F-102-15) – Engine Control Unit (ECU) A-028: Boost pressure plausibility check detects that the boost pressure is higher than expected

Under low engine speed and low load conditions, the Engine Control Unit (ECU) monitors the intake manifold pressure and compares it against the ambient atmospheric pressure. If the measured boost pressure is implausibly high for the current operating conditions, the ECU logs this fault code to indicate a potential sensor failure, wiring issue, or mechanical overboost condition.

• VESTRUM CVX
• Austoft 9900 series Sugarcane Harvesters
• Austoft 9000 series Sugarcane Harvesters
• Steiger tractors
• Magnum tractors
• Axial-Flow combines

1. 1

   Verify the code is currently active using the Case IH Electronic Service Tool (EST) or the operator's monitor

2. 2

   Locate and visually inspect the Boost Pressure and Air Temperature Sensor (B-FPT-48) on the intake manifold

3. 3

   Inspect the sensor wiring harness for a short circuit to ground on the signal wire, a short circuit to a voltage source, or open circuits

4. 4

   Check for damaged pins at the sensor connector or the ECU connector (Pins 207, 290, 237, 286)

5. 5

   Verify if the ECU A-028 has a software glitch that might require a reflash or update

1. 1

   Safely shut down the machine

   Turn the battery disconnect switch to the OFF position before disconnecting any engine management modules.

2. 2

   Inspect the B-FPT-48 sensor connector

   Disconnect the B-FPT-48 sensor connector and inspect the terminals for corrosion, pushed-back pins, or moisture. Clean and reseat if necessary.

3. 3

   Perform a continuity and voltage test

   Test the sensor harness back to the A-028 ECU. If a short to ground or open circuit is found in the wiring, repair or replace the damaged section of the engine harness.

4. 4

   Replace the sensor

   If the wiring tests good, the fault is likely an internal failure of the Boost Pressure and Air Temperature Sensor itself. Remove the old sensor from the intake manifold and install the new OEM replacement.

5. 5

   Check mechanical components

   If the sensor is reading accurately but the code persists, inspect the turbocharger's Variable Geometry Turbine (VGT) actuator or wastegate to ensure it is not mechanically stuck in a position that is forcing an actual overboost condition.

6. 6

   Clear Codes and Test

   Reconnect the battery, connect the EST, clear the inactive fault codes, and run the engine under varying loads to ensure the boost pressure plausibility check passes and the code does not return.