What is SPN 751 FMI 9 & How to Solve It?

What is SPN 751 FMI 9:

This code points to a fault in the shift selector or transmission range input, with signal abnormalities detected by the ECM.

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Why This Happens

• Loose or damaged shift selector wiring.
• Signal voltage outside expected parameters.
• Shift lever not returning to neutral or correct position.
• Transmission controller receiving unstable input.
  
  

How to Fix It

1. Inspect the shift selector and related wiring for faults.
2. Test signal voltage using diagnostic tools.
3. Adjust or replace selector components if physically worn.
4. Clear the code and test shifting behavior through all ranges.

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How to Avoid It Before It Happens

1. Inspect selector wiring and input response during servicing.
2. Replace worn selector switches and hardware.