SPN 111 [FMI 1 – 18] Trouble Codes Explained

SPN 111 is a diagnostic trouble code for Engine Coolant Level.

FMI 1 – Data Valid But Below Normal Operational Range – Most Severe
FMI 3 – Voltage Above Normal Or Shorted To High Source
FMI 4 – Voltage Below Normal Or Shorted To Low Source
FMI 17 – Data Valid But Below Normal Operating Range – Least Severe Level
FMI 18 -Data Valid But Below Normal Operating Range – Moderately Severe level

Coolant level, sensor, ECM

  • Safety first: Before working on your vehicle, ensure it is parked on a level surface, the engine is off, and the key is removed from the ignition. disconnect the negative battery terminal.
  • Check the coolant level: Open the hood and locate the coolant reservoir. Check the coolant level and ensure it is within the recommended range marked on the reservoir. If the coolant level is low, top it off and inspect the cooling system for leaks.
  • Inspect the cooling system: Visually inspect the cooling system components, including hoses, connections, the radiator, and the water pump, for any signs of leaks, damage, or wear. Repair or replace any damaged components as necessary.
  • Check the coolant level sensor: Locate the coolant level sensor, typically found on the coolant reservoir or radiator. Inspect the sensor for any signs of damage or corrosion. Ensure the electrical connector is properly seated and free of damage or corrosion.
  • Test the coolant level sensor: Use a multimeter to test the resistance of the coolant level sensor according to the manufacturer’s specifications. If the sensor’s resistance is out of the specified range, replace the sensor.
  • Inspect the wiring and connections: Check the wiring and connections between the coolant level sensor and the ECM for any signs of damage, corrosion, or loose connections. Repair or replace any damaged wiring or connectors as necessary.
  • Reconnect the battery and clear codes: reconnect the negative battery terminal and use a diagnostic scan tool to clear the stored fault codes.


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