What is SPN 111 & How to Solve It?

What is SPN 111

SPN 111: Refers to a fault related to the Engine Coolant Temperature Sensor, which measures the temperature of the engine coolant circulating through the cooling system.

When SPN 111 is triggered, it indicates that the Engine Coolant Temperature Sensor has either failed or is providing incorrect data to the ECM, potentially affecting engine temperature regulation and overall performance.

‍

Why It Happened

This fault code is usually caused by:

• A malfunctioning or damaged engine coolant temperature sensor.
  
• Faulty wiring or loose connections between the sensor and ECM.
  
• Insufficient coolant levels or a coolant leak.
  
• A failing thermostat that is not regulating the engine temperature correctly.
  
• A failure in the ECM’s processing of sensor data.
  
  

How to Resolve It

To fix SPN 111:

1. Check the coolant level and top it off if needed.
   
2. Inspect the engine coolant temperature sensor and wiring for damage or corrosion.
   
3. Replace the sensor if it is faulty.
   
4. Test the thermostat to ensure it’s working properly.
   
5. After repairs, clear the fault code and restart the engine to confirm the fix.
   
   

How to Avoid Before It Happens

To prevent SPN 111:

• Regularly check coolant levels and inspect the cooling system for leaks.
  
• Perform routine maintenance on the thermostat and sensors.
  
• Use an equipment management tool like Clue to monitor engine temperature data in real-time.