Case IH P32 – Engine Control Unit (EDC) / Powertrain Control Unit (PCU): Boost Air Pressure Sensor, Open Circuit Or Current Below Normal Range

The engine control system has detected a loss of signal from the boost air pressure sensor. The voltage or current returning from the sensor has dropped below the minimum acceptable threshold, causing the system to default to a preset boost pressure value and potentially put the engine into a low-output protection mode.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Visually inspect the boost air pressure sensor on the intake manifold and ensure the electrical connector is securely plugged in.

2. 2

   Inspect the wiring harness leading to the sensor for chafing, breaks, or melted insulation that could cause an open circuit.

3. 3

   Check resistance at the sensor terminals (approximately 3400 to 8200 Ω at 20°C between terminals 3 and 4) and verify the 5V reference voltage from the ECU.

4. 4

   Check for accompanying CAN BUS transmission errors (like T38 or T39) that might indicate a broader wiring harness issue rather than an isolated sensor failure.

1. 1

   Power Down

   Turn off the tractor, remove the key, and allow the engine to cool.

2. 2

   Locate the Sensor

   Find the boost air pressure sensor on the engine's intake manifold.

3. 3

   Disconnect and Clean

   Unplug the sensor's electrical connector. Spray the contacts with electrical contact cleaner to remove any dirt, oil, or corrosion. Reconnect and see if the code clears.

4. 4

   Test the Wiring

   If the code persists, use a multimeter to verify continuity between the sensor connector and the ECU harness to rule out a broken wire.

5. 5

   Replace the Sensor

   If the wiring is intact and receiving voltage, the sensor has failed internally. Unbolt the old sensor from the intake manifold, clean the mounting surface, and install the new sensor.

6. 6

   Clear Codes

   Reconnect the harness, turn the key to the ON position, and use your diagnostic tool (or the tractor's H-Menu configuration) to clear the stored fault codes.

7. 7

   Test Run

   Start the engine and verify that the tractor is no longer in low-output protection mode and the code does not return.