Case IH P50 – Engine Control Module (ECM / EDC) or Electronic Instrument Cluster (EIC): Incorrect code displayed because of XCM software / Coolant Temperature Sensor (PHY), Shorted To High Source

The control module is receiving a voltage signal from the Engine Coolant Temperature (ECT) sensor that exceeds the maximum normal operating range. This typically happens when the sensor's signal wire is shorted directly to a high-voltage power source, if there is an open circuit, or if the sensor has failed internally. Note: P50 is officially documented as 'Incorrect code displayed because of XCM software (download the latest software)', while the underlying coolant temperature sensor fault is T50.

• MXM
• MXM Series
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• Steiger
• Magnum
• AFX Combines
• AFX8010

1. 1

   Perform a sensor resistance test by disconnecting the engine coolant temperature sensor and using a multimeter to check for an internal short or failure.

2. 2

   Inspect the wiring harness between the sensor and the instrument controller/ECU for a short to a 12V/5V power source, a short to ground, or an open circuit.

3. 3

   If the sensor and wiring harness test good, check the instrument controller or ECU for internal faults.

1. 1

   Preparation

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical damage.

2. 2

   Locate the Sensor

   Find the coolant temperature sensor, usually located on the engine block or near the thermostat housing.

3. 3

   Inspect and Repair Wiring

   If your diagnostic checks revealed a short to a high voltage source in the wiring harness, locate the chafed or melted section of the wire. Splice and repair the damaged wiring, then wrap it in heat-shrink tubing and a protective loom.

4. 4

   Replace the Sensor (if defective)

   Place a catch pan under the engine, as removing the sensor will release some coolant. Unplug the electrical connector. Unscrew the defective sensor using a deep socket or wrench. Thread the new sensor into the housing and tighten to OEM specifications. Reconnect the electrical harness.

5. 5

   Reassembly and Clearing Codes

   Reconnect the battery. Top off any lost engine coolant. Turn the key on, clear the error log in the ECU, and restart the engine. Verify that the fault code does not return during the next driving cycle.