Case IH P24 – Engine Electronic Control Unit (EECU) / Engine Electronic Management (EEM / EEM3): Boost Air Temperature Sensor, Shorted To Low Source

The Boost Air Temperature Sensor signal voltage returning to the controller has dropped below the minimum acceptable threshold (near 0 volts). This indicates that the sensor's signal wire is shorted directly to ground, or the sensor itself has suffered an internal short circuit.

• 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
• Case IH Magnum
• Case IH Puma

1. 1

   Visual Harness Inspection: Inspect the wiring harness leading to the Boost Air Temperature Sensor for chafing, melted insulation, or pinched wires against the engine block that could cause a short to ground.

2. 2

   Disconnect Test: Disconnect the sensor. If the active fault code changes from 'Shorted to Low Source' (T24) to 'Open Circuit' (T23), the wiring is fine and the sensor itself is internally shorted.

3. 3

   Resistance Testing: Measure the resistance of the sensor across its pins. According to OEM specs, the sensor should read approximately 595 ohms at 60°C (2.170V), 322 ohms at 80°C (1.480V), and 186 ohms at 100°C (0.982V). If the multimeter reads near 0 ohms, the sensor is dead.

4. 4

   Harness Continuity Test: With the sensor and the ECU disconnected, probe the signal wire to a known good ground. If there is continuity, the wiring harness has a short to ground and must be repaired.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes to the EECU.

2. 2

   Locate the Sensor

   Locate the Boost Air Temperature Sensor on the engine. It is typically threaded into the charge air piping after the intercooler/cooler and before the EGR valve.

3. 3

   Remove the Sensor

   Depress the locking tab on the electrical connector and pull it off. Use a deep socket or wrench to carefully unthread the sensor from the intake manifold/piping.

4. 4

   Install the New Sensor

   Thread the new sensor into the port by hand to prevent cross-threading, then tighten to the OEM torque specification.

5. 5

   Wiring Repair (If Applicable)

   If the diagnostic checks proved the harness was shorted, locate the chafed wire, cut out the damaged section, solder in a new piece of wire, and seal it with marine-grade heat shrink.

6. 6

   Reassembly

   Reconnect the electrical pigtail to the sensor. Reconnect the battery.

7. 7

   Clear Codes

   Start the engine. Enter the tractor's H-Menu or use a diagnostic tool to clear the inactive fault codes and verify that T24 does not return.