Case IH 3172 (DTC F523) - ECU – Engine Control Unit (ECU) A-095: Engine coolant temperature has exceeded the pre-warning threshold

The engine coolant temperature sensor (B-016) has detected that the coolant temperature has surpassed the pre-warning limit of 106.0 °C (222.7 °F).

• MAXXUM T4E
• Case IH 240 Series Axial-Flow Combines
• Case IH Puma series
• Case IH Magnum series
• Case IH Farmall series (40-45-50 CVT, 95U-115U Pro EP)
• Case 580 Super N Backhoes
• Case Wheel Loaders

1. 1

   Verify if the fault is currently active to determine if it is a physical cooling issue or a stored code.

2. 2

   Check if an external power supply is connected to the battery, which can cause false readings; disconnect if present.

3. 3

   Inspect the physical cooling system for actual over-temperature conditions, including coolant level, external leaks, and radiator blockages (e.g., chaff or debris).

4. 4

   Test the Coolant Temperature Sensor (B-016) resistance (should be 332 Ω to 10.149K Ω between 80 °C and -10 °C).

5. 5

   Inspect wiring to ECU A-095 to ensure proper analog input signal (erratic resistance or voltage dropping below 0.188 V can cause false codes).

1. 1

   Safety First

   Safely shut down the engine and allow the machine to cool completely. Warning: Do not open the cooling system while the engine is hot and pressurized.

2. 2

   Clear Blockages

   If the diagnostic check revealed debris blocking the radiator or aftercooler, thoroughly clean the cooling package.

3. 3

   Repair Leaks

   If leaks were found during the visual inspection, repair the damaged hoses or radiator components and refill the system with the OEM-specified coolant.

4. 4

   Replace the Sensor

   If the physical cooling system is functioning normally but the B-016 sensor failed the resistance test, locate the Engine Coolant Temperature Sensor on the engine block/cylinder head. Disconnect the wiring harness, unscrew the faulty sensor, and install the replacement sensor.

5. 5

   Clear Codes

   Use the Case IH Electronic Service Tool (EST) to clear the fault codes from the ECU memory, as some codes require the tool to be fully wiped.

6. 6

   Test Run

   Run the machine under load to verify that the coolant temperature remains within the normal operating range and that code 3172 does not return.