Case IH t28 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Boost Air Temperature Sensor (PHY), Data Valid But Above Normal Range

The sensor's electrical circuit is intact, but the temperature value it is reporting to the computer is higher than the maximum acceptable operating threshold. This usually points to either a genuinely overheating intake charge (due to a blocked charge air cooler/intercooler or a failing turbocharger) or a sensor whose internal resistance has drifted out of calibration.

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

1. 1

   Verify Actual Temperature: Check the charge air cooler (intercooler) for blockages, dirt, or debris restricting airflow.

2. 2

   Inspect the Turbocharger: Ensure the turbocharger is functioning correctly and not overworking/superheating the air due to mechanical failure.

3. 3

   Wiring and Connector Inspection: Inspect the wiring harness leading to the Boost Air Temperature Sensor for chafed wires, melted insulation, or corrosion inside the connector plug.

4. 4

   Sensor Resistance Test: Using a multimeter, test the sensor's resistance at a known ambient temperature and compare it against the OEM service manual specifications to confirm if the sensor has drifted out of range.

1. 1

   Park the tractor on a level surface, turn off the engine, and remove the key. Disconnect the negative battery terminal to prevent electrical shorts.

   Park the tractor on a level surface, turn off the engine, and remove the key. Disconnect the negative battery terminal to prevent electrical shorts.

2. 2

   Locate the Boost Air Temperature Sensor, which is typically mounted directly on the intake manifold or the charge air piping leading from the intercooler to the engine.

   Locate the Boost Air Temperature Sensor, which is typically mounted directly on the intake manifold or the charge air piping leading from the intercooler to the engine.

3. 3

   Carefully depress the locking tab on the electrical connector and pull it free from the sensor.

   Carefully depress the locking tab on the electrical connector and pull it free from the sensor.

4. 4

   Using an appropriately sized deep socket or wrench, unthread the faulty sensor from the intake manifold.

   Using an appropriately sized deep socket or wrench, unthread the faulty sensor from the intake manifold.

5. 5

   Clean the mounting port threads on the manifold to ensure a good seal.

   Clean the mounting port threads on the manifold to ensure a good seal.

6. 6

   Thread the new OEM Boost Air Temperature Sensor into the port by hand to prevent cross-threading, then tighten to the manufacturer's specified torque.

   Thread the new OEM Boost Air Temperature Sensor into the port by hand to prevent cross-threading, then tighten to the manufacturer's specified torque.

7. 7

   Reconnect the electrical harness plug until it clicks securely into place.

   Reconnect the electrical harness plug until it clicks securely into place.

8. 8

   Reconnect the battery.

   Reconnect the battery.

9. 9

   Turn the key to the ON position and use the tractor's H-Menu (diagnostic display) or an electronic service tool to clear the stored t28 fault code. Start the engine and verify the code does not return under load.

   Turn the key to the ON position and use the tractor's H-Menu (diagnostic display) or an electronic service tool to clear the stored t28 fault code. Start the engine and verify the code does not return under load.