Case IH F-1136-21 - ECU – Engine Control Unit (ECU): ECU temperature sensor 2 is too low

The secondary temperature sensor monitoring the Engine Control Unit (ECU) is registering a physical signal or voltage that has fallen below the minimum acceptable operational limit. This condition is typically caused by an open circuit, a short to ground, or a failure of the internal temperature sensor itself.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines

1. 1

   Check for related ECU temperature codes (such as F-1136-00, F-1136-12, F-1136-20, or F-1136-31) to confirm if the sensor has failed entirely or is shorting out

2. 2

   Inspect the main wiring harness connecting to the ECU for signs of corrosion, moisture ingress, or backed-out pins that could cause an open circuit or high resistance

3. 3

   Ensure the ECU is receiving proper voltage and has a clean, solid ground connection to the chassis, as poor grounding can cause erratic internal sensor readings

4. 4

   Clear the fault code using the Case IH Electronic Service Tool (EST) and cycle the key to see if the code is active or was a momentary glitch

1. 1

   Turn off the machine and disconnect the battery to prevent electrical spikes.

   Turn off the machine and disconnect the battery to prevent electrical spikes.

2. 2

   Disconnect the main harnesses from the Engine Control Unit.

   Disconnect the main harnesses from the Engine Control Unit.

3. 3

   Clean the connectors with electrical contact cleaner and apply dielectric grease.

   Clean the connectors with electrical contact cleaner and apply dielectric grease. Reconnect the harnesses, ensuring they lock securely into place.

4. 4

   Reconnect the battery, turn the key on, and use the diagnostic tool to clear the code.

   Reconnect the battery, turn the key on, and use the diagnostic tool to clear the code.

5. 5

   Run the engine.

   Run the engine. If code F-1136-21 returns, the internal temperature sensor has failed.

6. 6

   Note: The ECU temperature sensor is integrated into the ECU circuit board and cannot be serviced individually.

   Note: The ECU temperature sensor is integrated into the ECU circuit board and cannot be serviced individually. If the sensor fails, the entire Engine Control Unit must be replaced.

7. 7

   Install the replacement ECU and have an authorized Case IH dealer flash/program the new module.

   Install the replacement ECU and have an authorized Case IH dealer flash/program the new module with the correct software payload for your specific machine's VIN/serial number.