What is SPN 4364 FMI 1 & How to Solve It?

What is SPN 4364 FMI 1:

SPN 4364 FMI 1 indicates a fault with the Exhaust Gas Temperature Sensor Circuit – Signal Below Normal. This means the engine control module (ECM) is receiving an exhaust gas temperature signal that is lower than expected, which can affect engine performance, emissions control, and the functionality of components such as the turbocharger or aftertreatment systems.

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Why This Happens

Common causes include:

• Faulty or damaged exhaust gas temperature sensor.
  
• Wiring issues such as short circuits or open circuits.
  
• Sensor contamination or physical damage.
  
• Faulty ECM or sensor calibration problems.

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How to Fix It

To resolve this fault:

1. Inspect the exhaust gas temperature sensor and wiring for damage or corrosion.
   
2. Test the sensor for proper voltage or resistance values and replace if faulty.
   
3. Check the wiring and connectors for any visible damage or looseness.
   
4. Clear the fault code and verify the sensor is functioning correctly.

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How to Avoid It Before It Happens

Prevent this fault by:

• Regularly inspecting the exhaust gas temperature sensor and wiring.
  
• Ensuring electrical connections are clean, secure, and corrosion-free.
  
• Performing routine diagnostics to detect sensor issues early.
• Use Clue’s Preventive Maintenance to schedule regular inspections of the exhaust gas temperature sensor and wiring to ensure they’re functioning correctly before they impact engine performance.