What is SPN 412 FMI 16 & How to Solve It?

What is SPN 412 FMI 16:

SPN 412 refers to the Throttle Valve Position, and FMI 16 means the signal is plausible but drifting outside normal trends.

This fault may not cause immediate failure but signals that throttle response may be degrading.

‍

Why This Happens

• Throttle position sensor drifting or losing accuracy.
  
• ECM struggling to interpret throttle changes.
  
• Wiring resistance increasing due to corrosion.
  
• Valve motor slow or partially stuck.
  

‍

How to Fix It

1. Inspect and test throttle position sensor with scan tool.
   
2. Replace sensor if voltage output is unstable.
   
3. Clean throttle body if sticky or delayed movement is noted.
   
4. Inspect wiring and connectors for resistance or looseness.
   
5. Clear the code and confirm throttle stability in real-time data.
   

‍

How to Avoid It Before It Happens

1. Replace throttle sensors before 8,000 hours or per OEM.
   
2. Clean throttle bodies every 1,000 hours.
   
3. Secure wiring away from heat or vibration.
   
4. Track idle and throttle response to identify lag.