What is SPN 168 FMI 17 & How to Solve It?

What is SPN 168 FMI 17:

SPN 168 is a battery voltage code, and FMI 17 means the voltage signal is decreasing or unstable over time.

This code warns that system voltage is falling below acceptable range, which can affect ECM and sensor operation.

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Why This Happens

• Battery voltage dropping under load.
  
• Alternator undercharging or failing.
  
• Corroded battery terminals or ground cables.
  
• ECM power feed wiring issue.
  

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How to Fix It

1. Test battery voltage with key on and engine off.
   
2. Measure alternator output during engine run.
   
3. Inspect ground cables and terminals for corrosion.
   
4. Replace battery or alternator as needed.
   
5. Clear the code and monitor voltage stability.
   

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How to Avoid It Before It Happens

1. Test charging system performance quarterly.
   
2. Clean terminals and tighten battery clamps regularly.
   
3. Replace aging alternators proactively.
   
4. Avoid running accessories while engine is off.
5. Leverage Clue’s Equipment Tracking to monitor battery voltage and alternator performance in real time, detecting voltage instability before it affects system performance.