What is SPN 520210 FMI 1 & How to Solve It?

What is SPN 520210 FMI 1:

SPN 520210 FMI 1 indicates a fault with the Exhaust Gas Temperature (EGT) Sensor Circuit, Low Voltage. This means the sensor is detecting a voltage lower than expected, signaling that the exhaust gas temperature measurement is below the normal range. Accurate EGT readings are critical for managing emissions and protecting engine components from excessive heat.

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Why This Happens

• Faulty or failing EGT sensor.
  
• Damaged, broken, or corroded wiring or connectors in the sensor circuit.
  
• Open circuit or wiring harness damage.
  
• Sensor contamination or soot buildup affecting readings.
  
• Engine control module malfunction.
  
  

How to Fix It

1. Inspect the EGT sensor wiring and connectors for damage, corrosion, or looseness.
   
2. Test the EGT sensor for proper resistance and signal output.
   
3. Clean or replace the sensor if contaminated or faulty.
   
4. Repair or replace any damaged wiring or connectors.
   
5. Check the engine control module for faults or software updates.
   
6. Clear the fault code and verify the repair by monitoring sensor performance.
   
   

How to Avoid It Before It Happens

• Regularly inspect and clean the EGT sensor and wiring.
  
• Prevent sensor contamination by maintaining the exhaust system.
  
• Protect wiring from moisture and physical damage.
  
• Schedule routine diagnostics to detect sensor or wiring issues early.
• Use construction preventive maintenance software to avoid breakdowns.