Case IH 151 – Engine Controller (ENG): Coolant Temperature level has exceeded the warning limit.

This is an Engine Protection code triggered when the sensor detects that the engine coolant has reached a temperature high enough to risk gradual or sudden engine overheating. It can be caused by a genuine overheating event (low coolant, blocked radiator) or a faulty coolant temperature sensor/circuit.

• MX Magnum
• STX Steiger
• MX Magnum series
• Steiger series
• STX series
• STX440
• Maxxum
• TG Series
• TG210
• TG230
• TG255
• TG285
• T8
• T9

1. 1

   Check coolant level in the reservoir and radiator (do not open when hot)

2. 2

   Inspect for visible coolant leaks around radiator hoses, the water pump, and the engine block

3. 3

   Inspect the radiator, charge air cooler, and front grille for dust, chaff, or debris blockages that could restrict airflow

4. 4

   Ensure the engine cooling fan/fan clutch is engaging properly

5. 5

   Locate the Coolant Temperature Sensor on the engine block/thermostat housing and inspect the electrical connector and wiring harness for corrosion, moisture, melted wires, or shorts to ground

1. 1

   Cool Down

   Shut down the tractor and allow the engine to cool completely to avoid severe burns.

2. 2

   Clear Blockages & Refill

   Blow out the radiator fins with compressed air if clogged. Top off the engine coolant if it is low.

3. 3

   Repair Wiring

   If the diagnostic checks revealed chafed wires or a broken connector at the sensor, splice in a new pigtail connector or repair the wiring harness.

4. 4

   Replace the Sensor

   If the tractor is not actually overheating (e.g., the code triggers immediately on a cold start) and the wiring is intact, the sensor has likely failed. Drain a small amount of coolant from the system so the level is below the sensor port. Disconnect the electrical harness from the sensor. Unthread the old sensor and install the new OEM sensor. Reconnect the wiring harness.

5. 5

   Test and Clear

   Refill the drained coolant. Start the engine, monitor the temperature gauge on the dash, and use a diagnostic tool to clear Fault Code 151.