Case IH F-1136-31 - ECU – Engine Control Unit (ECU): ECU temperature sensor 1 is too low

The Engine Control Unit (ECU) contains an internal temperature sensor to monitor its own operating temperature. This code triggers when the voltage or temperature reading from this internal sensor drops below the minimum acceptable threshold. A failed sensor can cause the engine to fuel incorrectly, leading to hard starting, under-fueling, or incorrect timing, especially in cold weather.

• MAGNUM AFS Connect
• Magnum AFS Connect (250, 280, 310, 340, 380, 400)
• Steiger (350-620)
• Quadtrac
• Puma
• Optum
• Patriot Sprayers
• Axial-Flow Combines (240 series)

1. 1

   Verify if the machine is operating in extreme cold, which might cause the sensor to legitimately read below its minimum threshold

2. 2

   Check the main ECU wiring harness and ground connections for severe voltage drop, short to ground, or moisture intrusion at the ECU connector

3. 3

   Connect the Case IH Electronic Service Tool (EST) to check for active software updates, as false internal temperature anomalies are sometimes resolved via an ECU reflash

4. 4

   Clear the code. If F-1136-31 returns immediately as an active fault at normal operating temperatures, the internal ECU temperature sensor has suffered a hardware failure

1. 1

   Disconnect Power

   Disconnect the negative battery terminal to prevent electrical arcing or voltage spikes.

2. 2

   Locate the ECU

   Locate the Engine Control Unit, typically mounted directly to the side of the FPT engine block.

3. 3

   Disconnect Harnesses

   Carefully release the locking levers on the main wiring harness connectors and unplug them from the ECU.

4. 4

   Remove the ECU

   Remove the mounting bolts securing the ECU to the engine block/vibration isolators and remove the faulty unit.

5. 5

   Install the New ECU

   Mount the replacement or remanufactured ECU and torque the bolts to OEM specifications.

6. 6

   Reconnect

   Reconnect the wiring harnesses, ensuring the locking levers seat fully, then reconnect the battery.

7. 7

   Programming

   Use the Case IH Electronic Service Tool (EST) to flash the correct software payload for the specific tractor model and perform necessary calibrations (such as entering the injector trim codes).