What is SPN 629 FMI 11 & How to Solve It?

What is SPN 629 FMI 11:

SPN 629 FMI 11 refers to a problem with the Coolant Temperature Sensor Circuit. FMI 11 suggests that the signal from the coolant temperature sensor is out of the expected range, typically due to a high voltage condition, affecting engine cooling and potentially leading to overheating or poor engine performance.

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Why This Happens:

• Faulty coolant temperature sensor.
  
• Damaged or shorted wiring in the sensor circuit.
  
• Corroded or loose sensor connectors.
  
• Low coolant levels causing improper sensor readings.
  
• ECM misinterpretation of the sensor signal.
  
  

How to Fix It:

1. Inspect the coolant temperature sensor for visible damage.
   
2. Test the sensor to verify it is providing accurate voltage and resistance readings.
   
3. Check wiring and connectors for damage, corrosion, or loose connections.
   
4. Replace the faulty coolant temperature sensor if necessary.
   
5. Verify coolant levels and ensure the system is functioning properly.
   
   

How to Avoid It Before It Happens:

• Regularly inspect the coolant temperature sensor and its wiring.
  
• Keep connectors clean and free from corrosion.
  
• Maintain proper coolant levels and replace coolant as needed.
  
• Use diagnostic tools to monitor the sensor’s performance.
  
• Clue’s Equipment Maintenance services help monitor coolant systems and prevent temperature sensor-related issues from affecting engine operation.