Case IH 3257 – Engine Control Module (ECM) / Electronic Diesel Control (EDC): Turbine Speed and Air Pressure Too High

Indicates an overboost condition where the turbocharger's turbine speed and/or the intake manifold boost pressure has exceeded the maximum allowable limits programmed into the engine's software.

• Case IH Magnum Series (Magnum 180, 235–340 Series 4)
• Case IH Puma Series
• Case IH Maxxum Series

1. 1

   Check the boost pressure sensor (MAP sensor) and the turbocharger speed sensor for accurate readings, as a failed sensor can falsely report high pressure or speed.

2. 2

   Inspect the wiring harnesses and connectors leading to the boost pressure sensor and turbo speed sensor for shorts to the battery, shorts to ground, or open circuits.

3. 3

   Check the Variable Geometry Turbocharger (VGT) actuator or wastegate mechanism to see if it is mechanically stuck closed or sticking, causing a genuine overboost.

4. 4

   Ensure there are no blockages in the intake filter or exhaust system that could cause abnormal pressure differentials.

1. 1

   Inspect Wiring

   Visually and electrically test the harness from the ECM to the boost pressure sensor and turbo speed sensor. Repair any chafed wires or corroded connector pins.

2. 2

   Test/Replace Sensors

   If the wiring is intact but the ECM is receiving out-of-range voltage readings (too high/too low), replace the boost pressure sensor and/or turbo speed sensor.

3. 3

   Service the Turbo Actuator

   If the sensors are reading accurately, the turbocharger is genuinely overboosting. Inspect the wastegate or VGT actuator for free movement. Clean the mechanism if it is binding. If the actuator has failed internally, replace the actuator or the turbocharger assembly.

4. 4

   Clear and Test

   Use the CNH EASy diagnostic tool to clear the fault code (and any associated FPT 19B codes). Run the machine under load to verify the boost pressure remains within normal parameters and the code does not return.