What is SPN 4 & How to Solve It?

What is SPN 4

SPN 4, Refers to a fault related to the Engine Control Module (ECM) and indicates a problem with the Engine Coolant Temperature sensor.

When SPN 4 is triggered, it suggests that the engine coolant temperature is either too high or too low, or the sensor is not transmitting correct data to the ECM.

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Why It Happened

The common causes for this fault code include:

• Low coolant levels or coolant leaks.
  
• A malfunctioning engine coolant temperature sensor.
  
• Faulty wiring or loose connections between the sensor and ECM.
  
• A malfunctioning thermostat.
  
• Issues with the ECM in processing the sensor’s data.
  
  

How to Resolve It

To resolve SPN 4:

1. Inspect and refill coolant if necessary.
   
2. Check the coolant temperature sensor and replace it if faulty.
   
3. Inspect the thermostat to ensure it’s functioning properly.
   
4. Check for any loose or damaged wiring between the sensor and ECM.
   
5. After repairs, clear the fault code and restart the system to confirm the fix.
   
   

How to Avoid Before It Happens

To avoid SPN 4:

• Regularly check coolant levels and inspect the cooling system.
  
• Perform routine maintenance on the sensor, thermostat, and wiring.
  
• Use Clue to track engine temperature in real-time and receive alerts on abnormal readings.