Case IH 51138 – AUX (Auxiliary Remote Valve Controller): Invalid Software Instruction Executed

This fault code indicates an internal software or memory error. The controller attempted to execute a software command that it did not recognize or that was corrupted. This is typically caused by a software glitch, a voltage irregularity corrupting the processor's operation, or a physical failure of the controller's internal memory/processor.

• MX Magnum
• Case IH MX Magnum series
• Case IH TG series
• Case IH Steiger series
• Case IH Puma series

1. 1

   Check System Voltage: Ensure the alternator is outputting correctly and batteries are fully charged. Look for accompanying voltage fault codes (such as AUX 8011) which can cause memory errors.

2. 2

   Inspect Harness Connections: Verify the power, ground, and CAN bus connections to the AUX controller. The CAN data bus wires (typically yellow and green) should measure approximately 2.4V to 2.5V.

3. 3

   Check for Communication Codes: Look for code 12021 (Communications Lost with Auxiliary Controller) or similar CAN bus errors, which indicate a wiring issue rather than an internal software failure.

4. 4

   Clear and Retest: Clear the fault codes and cycle the key. If the code was caused by a momentary voltage drop during cranking, it may not return.

1. 1

   Reflash the Controller

   Connect the CNH Electronic Service Tool (EST). Attempt to reflash the AUX controller with the latest software version. A software update or re-installation can often overwrite corrupted memory sectors causing the 'Invalid Instruction' error.

2. 2

   Replace the Controller

   If the EST cannot communicate with the controller, the flash fails, or the 51138 code returns immediately after a successful reflash, the internal processor/EEPROM has failed. The AUX controller must be replaced.

3. 3

   Calibrate

   After installing a new AUX controller, you must use the EST or the tractor's onboard instrumentation display to perform the Remote Hydraulics Controller Calibration procedure so the new module can learn the valve limits and flow parameters.