What is SPN 3217 FMI 20 & How to Solve It?

What is SPN 3217 FMI 20:

SPN 3217 FMI 20 indicates a low voltage signal in the Transmission Fluid Temperature Sensor Circuit. FMI 20 means that the ECM (Engine Control Module) has detected that the voltage from the sensor is below the expected range, which can affect the transmission's performance by causing incorrect fluid temperature readings.

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Why This Happens:

• Faulty transmission fluid temperature sensor.
  
• Damaged or shorted wiring in the sensor circuit.
  
• Corroded or loose sensor connectors.
  
• Low transmission fluid levels.
  
• ECM failure to interpret the sensor signal properly.
  
  

How to Fix It:

1. Inspect the transmission fluid temperature sensor for visible damage or wear.
   
2. Check the wiring and connectors for signs of corrosion, shorts, or loose connections.
   
3. Test the sensor’s voltage and resistance readings to ensure they match manufacturer specifications.
   
4. Replace the sensor if it’s faulty or providing inaccurate readings.
   
5. Inspect transmission fluid levels and top off or replace fluid if necessary.

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How to Avoid It Before It Happens:

• Regularly inspect the transmission fluid temperature sensor and wiring.
  
• Ensure proper fluid levels and maintenance for the transmission system.
  
• Check connectors regularly to avoid corrosion or moisture buildup.
  
• Use diagnostic tools to monitor fluid temperature and sensor performance.
  
• Clue offers Equipment Maintenance services to proactively monitor sensor health and ensure your transmission fluid system operates at peak performance.