Case IH 235 – Engine Control Unit (ECU): Engine Coolant Level is low. Add coolant fluid.

The engine controller detects a low voltage signal on the coolant level sensor circuit (such as pin 22 of the sensor harness connector), indicating that the radiator coolant level has dropped below the safe threshold. This condition causes a progressive engine power de-rate and can trigger an automatic engine shutdown to protect the engine from overheating damage.

• MX Magnum
• STX Steiger
• Magnum Tractors (235, 260, 290, 315, 340)
• Combines (AFX8010, 1640 through 2588)
• Steiger series
• CX series
• MX series
• 7110-9280 series

1. 1

   Physically inspect the coolant level in the deaeration tank/radiator to confirm if the fluid is actually low.

2. 2

   Inspect all coolant pipes, hoses, and the radiator for visible leaks.

3. 3

   Check the wiring harness leading to the coolant level sensor for damaged wires, bent, loose, or corroded pins, and loose connectors.

4. 4

   Disconnect the sensor connector (e.g., connector P30) and turn the ignition key to the ON position to check for a 5V supply at the designated signal pin (e.g., Pin C).

1. 1

   Cool Down

   Allow the engine to cool completely before opening the cooling system to prevent injury.

2. 2

   Refill Coolant

   If the fluid is genuinely low, refill the engine coolant to the proper specification level in the reservoir.

3. 3

   Repair Leaks

   If you identified any leaking pipes or hoses during the diagnostic phase, replace or repair them.

4. 4

   Repair Wiring

   If the fluid level is correct but the wiring harness failed the visual inspection or voltage test, repair the damaged wires or replace the harness section.

5. 5

   Replace Sensor

   If the coolant level is full, the wiring is intact, and the 5V reference signal is present at the connector, remove the faulty coolant level sensor and install a replacement.

6. 6

   Clear Codes

   Clear the fault codes from the Engine ECU and run the machine to verify the code does not return and the warning lamps remain off.