What is SPN 100 FMI 17 & How to Solve It?

Learn what SPN 100 FMI 17 means, its causes, and how to fix it. Follow our simple guide to resolve the issue and get your equipment running smoothly again.

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Table of Content

What is SPN 100 FMI 17

  • SPN 100: Refers to a fault related to the engine coolant temperature sensor, indicating that the ECM is receiving coolant temperature data that is out of range or invalid.
  • FMI 17: Indicates that the sensor is reporting a voltage signal that is higher than expected, meaning the ECM is receiving unusually high voltage from the sensor.

Together, SPN 100 FMI 17 signals that the coolant temperature sensor is malfunctioning and providing a voltage signal that the ECM cannot process, which could lead to improper engine cooling and temperature regulation.

Why It Happened

This fault code typically arises from:

  • Faulty coolant temperature sensor: The sensor may be malfunctioning or providing incorrect voltage signals.
  • Wiring issues: Damaged or frayed wiring between the sensor and ECM could cause incorrect voltage readings.
  • Contaminated coolant: Contaminants in the coolant can affect sensor readings and cause inaccurate data.
  • Thermostat failure: If the thermostat is malfunctioning, it could prevent proper coolant flow, leading to irregular temperature readings.


How to Resolve It

To resolve SPN 100 FMI 17:

  1. Check the coolant temperature sensor: Inspect the sensor for damage and replace if necessary.
  2. Inspect wiring and connections: Look for any damaged or corroded wiring between the sensor and ECM.
  3. Test the thermostat: Ensure the thermostat is regulating the coolant temperature properly.
  4. Test coolant quality: Check coolant for contamination and replace it if needed.
  5. Clear the fault code: After repairs, clear the fault code and restart the engine to verify the fix.

How to Avoid Before It Happens

To prevent SPN 100 FMI 17:

  • Regularly inspect the coolant temperature sensor and wiring.
  • Perform regular coolant changes to prevent contamination and ensure proper temperature regulation.
  • Use Clue to monitor coolant temperature data in real-time and get early alerts on sensor or cooling system issues.

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