Case IH P4F – Engine Control Module (ECM): Coolant Temperature Sensor (PHY), Data Incorrect

This code indicates that the engine control system is receiving an implausible or erratic signal from the engine coolant temperature sensor. The data being sent does not align with expected parameters (e.g., it may conflict with the engine oil temperature sensor, or the temperature is not rising as expected after the engine has been running).

• MXM
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• TM120
• TM130
• TM140
• TM155

1. 1

   Verify that the engine coolant is at the proper level in the header tank to rule out air pockets causing erratic readings.

2. 2

   Inspect the wiring harness leading to the coolant temperature sensor for chafing, melted insulation, or a short to ground.

3. 3

   Disconnect the sensor and check the pins for corrosion, water ingress, or loose connections.

4. 4

   Use a multimeter to test the resistance of the engine coolant temperature sensor across its pins and compare against a known temperature/resistance chart. An open or shorted circuit indicates a failed sensor.

1. 1

   Cool Down

   Ensure the tractor engine is turned off and has completely cooled down to prevent severe burns from pressurized, hot coolant.

2. 2

   Locate the Sensor

   Open the tractor hood and locate the engine coolant temperature sensor (typically threaded into the cylinder head or near the thermostat housing).

3. 3

   Disconnect

   Unplug the electrical harness connector from the sensor.

4. 4

   Remove the Sensor

   Place a catch pan under the engine to catch any escaping coolant. Use a wrench to unthread the sensor (M12 x 1.5 thread) from the engine block.

5. 5

   Install the New Sensor

   Thread the new coolant temperature sensor into the port. Tighten to the OEM torque specification (do not overtighten, as it is a brass fitting).

6. 6

   Reconnect

   Plug the electrical connector back into the new sensor.

7. 7

   Refill and Bleed

   Top up the engine coolant to the "MAX" line on the header tank.

8. 8

   Clear and Test

   Turn the key to the ON position, clear the inactive T4F fault code from the EIC, and start the engine. Let it reach operating temperature to ensure the code does not return and there are no coolant leaks.