New Holland ENG 3985 – Engine ECU: Engine ECU Temperature is High

The internal temperature sensor within the Engine Control Unit has detected a temperature exceeding the safe operating threshold, which can lead to component damage or unexpected engine shutdowns to protect the module.

• L220
• L175
• SR130
• SR160
• SR175
• SR175B
• B90B
• B100B
• E50B

1. 1

   Locate the Engine ECU in the engine bay and check for heavy accumulations of dirt, mud, or debris covering the module that could insulate it and cause overheating.

2. 2

   Ensure the machine's primary cooling system (radiator, cooling fan, and fan belt) is functioning properly to prevent engine bay overheating.

3. 3

   Use an infrared thermometer to measure the physical surface temperature of the Engine ECU and compare it to the diagnostic tool reading. If physically cool but reading hot, the internal sensor has failed.

4. 4

   Inspect the wiring harness connected to the ECU for shorts to power or ground, which can cause excessive current draw and internal overheating.

1. 1

   Clean ECU casing

   If the ECU is covered in debris, thoroughly clean the module's casing and the surrounding mounting area to restore airflow. Clear the fault code using a DTC eraser or diagnostic tool and test-run the machine under load to see if the code returns.

2. 2

   Repair cooling system

   If the engine bay is overheating, repair the underlying cooling system issue (e.g., clean the radiator, replace the fan drive) to resolve external heat sources.

3. 3

   Replace Engine ECU

   If the ECU is physically overheating due to an internal short, or if the internal temperature sensor has failed (reading hot when physically cool), the Engine ECU cannot be serviced internally and must be replaced.

4. 4

   Reprogram new ECU

   Flash/program the new module with the correct machine software, and write the ECU serial number to the system using the CNH Electronic Service Tool (EST).