What is SPN 84 FMI 19 & How to Solve It?

What is SPN 84 FMI 19:

SPN 84 FMI 19 refers to a high voltage issue in the Engine Coolant Temperature Sensor Circuit. FMI 19 indicates that the ECM is receiving a voltage that is higher than expected from the coolant temperature sensor, which can lead to inaccurate readings and potentially cause engine overheating.

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Why This Happens:

• Faulty engine coolant temperature sensor.
  
• High voltage supply affecting sensor output.
  
• Shorted or damaged wiring in the sensor circuit.
  
• Loose or corroded sensor connectors.
  
• ECM misinterpretation of the sensor’s signal.
  
  

How to Fix It:

1. Inspect the engine coolant temperature sensor for visible damage or malfunction.
   
2. Test the sensor’s signal to ensure it is within manufacturer specifications.
   
3. Check wiring and connectors for damage or corrosion.
   
4. Replace the faulty sensor if necessary.
   
5. Ensure that the ECM is receiving the correct sensor data.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the coolant temperature sensor and wiring.
  
• Perform routine coolant system maintenance to ensure accurate readings.
  
• Keep connectors clean and free from corrosion.
  
• Perform diagnostic checks to monitor sensor performance.
  
• Clue’s Equipment Maintenance services track coolant system sensors to help prevent overheating and ensure optimal engine health.