What is SPN 94 FMI 18 & How to Solve It?

What is SPN 94 FMI 18:

SPN 94 FMI 18 refers to a problem with the Engine Coolant Temperature Sensor. FMI 18 indicates that the ECM has detected a low voltage condition from the sensor, which can cause inaccurate coolant temperature readings and lead to engine overheating or poor performance.

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Why This Happens:

• Faulty coolant temperature sensor.
  
• Damaged or shorted wiring in the sensor circuit.
  
• Loose or corroded connectors in the sensor circuit.
  
• Low coolant levels preventing the sensor from detecting accurate temperatures.
  
• ECM misinterpreting the sensor's data due to a communication issue.
  
  

How to Fix It:

1. Inspect the coolant temperature sensor for visible damage or malfunction.
   
2. Test the voltage and resistance from the sensor to ensure it meets specifications.
   
3. Check wiring and connectors for damage, corrosion, or loose connections.
   
4. Replace the faulty sensor if necessary.
   
5. Ensure the coolant levels are correct and the system is functioning properly.
   
   

How to Avoid It Before It Happens:

• Perform regular inspections of the coolant temperature sensor and wiring.
  
• Maintain proper coolant levels and replace coolant as recommended.
  
• Check connectors and wiring for signs of wear or corrosion.
  
• Use diagnostic tools to monitor sensor health and avoid potential overheating.
  
• Clue’s Equipment Maintenance services offer continuous monitoring to keep track of sensor performance and detect problems before they affect engine operation.