Case IH 3173 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Engine coolant temperature has exceeded the warning threshold

The Engine Control Unit (ECU) monitors the engine coolant temperature sensor. A pre-warning is triggered when the engine coolant temperature exceeds 106.0 °C (222.7 °F), and a critical warning is triggered when it exceeds 110.0 °C (229.9 °F). When this code is logged, the engine management system will often initiate a torque limitation (engine power loss) to protect the engine from severe overheating damage.

• Steiger T4B
• 240 Series Axial-Flow Combines (7120, 7140, 8120, 9010)
• Puma series
• Farmall series (115U, 75C, 110A)
• Magnum series
• CX series (C50-CX100)
• Case 580 Super N backhoes
• Skid steer loaders (SSL)
• Compact track loaders (CTL)

1. 1

   Visual Cooling System Inspection: Check the radiator and aftercooler for blockages, dirt, or debris that could restrict airflow.

2. 2

   Coolant Level Check: Ensure the engine coolant is at the proper level in the expansion tank/radiator.

3. 3

   Fan Operation: Verify that the cooling fan is operating correctly and that the fan speed signal is being measured by the ECU.

4. 4

   Sensor & Wiring Check: Test the engine coolant temperature sensor (thermistor) and its wiring harness. Look for a short to ground (which causes a low voltage reading) or an open circuit/short to +V (which causes a high voltage reading).

5. 5

   Operating Conditions: Determine if the machine was simply overheating due to heavy, intensive use in high ambient temperatures.

1. 1

   Safety First

   Always shut down the engine and allow it to cool completely before opening the cooling system or working near the high-pressure fuel and cooling lines.

2. 2

   Clear Blockages

   If the radiator or cooling package is clogged with chaff or dirt, blow it out with compressed air.

3. 3

   Top Up Fluids

   If the coolant level is low, inspect for leaks and fill the system with the OEM-specified coolant.

4. 4

   Test/Replace the Sensor

   If the cooling system is mechanically sound but the ECU is reading erratic or falsely high temperatures, locate the engine coolant temperature sensor. Disconnect the wiring harness and test the sensor's resistance. If it is out of specification or the wiring is damaged, replace the sensor.

5. 5

   Installation

   Thread the new coolant temperature sensor into the engine block/housing. For NEF engines, an M14 temperature sensor should be torqued to 17 - 23 Nm (12.5 - 17.0 lb ft).

6. 6

   Clear Codes

   Reconnect the wiring harness. Use the Case IH Electronic Service Tool (EST) to clear the fault codes from the ECU memory, as the code may remain stored even after the physical repair is made.