Case IH P25 – Engine Control Unit (ECU) / EDC 7 / VECU: Boost Air Temperature Sensor, Data Valid But Above Normal Range

The Boost Air Temperature Sensor is sending a signal that is electrically valid (not shorted or open), but the temperature reading is above the normal operating range.

• MXM
• Case IH MXM Series (MXM 120, 130, 140, 155, 175, 190)
• Case IH Maxxum Series
• Case IH Magnum Series

1. 1

   Resistance Test: Measure the resistance of the NTC thermistor sensor and compare it to the temperature specifications (120°C = 112 ohms (0.643V), 100°C = 186 ohms (0.982V), 80°C = 322 ohms (1.480V), 60°C = 595 ohms (2.170V)).

2. 2

   Wiring Continuity: Check the continuity of the engine wiring harness between the ECU connector and the sensor connector.

3. 3

   Insulation Check: Verify the insulation of each wire to ensure there are no shorts to ground or to a high voltage source.

4. 4

   Visual Inspection: Inspect the sensor connector and ECU pins for corrosion, moisture, or pushed-out pins.

1. 1

   Locate the Sensor

   Find the boost air temperature sensor, which is mounted on the intake manifold / suction pipe.

2. 2

   Disconnect Battery

   Disconnect the negative battery terminal to prevent electrical spikes.

3. 3

   Disconnect Harness

   Unplug the electrical connector from the boost air temperature sensor.

4. 4

   Remove Sensor

   Carefully unscrew the faulty sensor from the intake manifold.

5. 5

   Install New Sensor

   Thread the new sensor into the manifold. Torque to the manufacturer's specification (do not overtighten, as it can damage the thermistor element).

6. 6

   Reconnect

   Plug the electrical harness back into the sensor and reconnect the battery.

7. 7

   Clear Codes

   Use the tractor's H-Menu or an Electronic Service Tool to clear the T25 fault code. Run the engine to operating temperature to verify the code does not return.