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SPN 110 FMI 15

Engine Coolant Temperature — Value too high (least severe).
The reading is above normal, but only at the lowest warning level.

What the SPN covers: Temperature of the engine coolant, usually measured near the thermostat housing. More on SPN 110.

What FMI 15 usually points to: An early warning: mild over-temperature or over-pressure, or a sensor starting to drift high. More on FMI 15.

Severity

STOP — shut down if the condition is real

If the engine is truly overheating, stop and let it cool. Never open a hot radiator cap.

Likely causes

  1. Low coolant level or leak
  2. Stuck thermostat
  3. Fan clutch or fan drive not engaging
  4. Plugged radiator or debris on the cooling stack
  5. Failed water pump
  6. Sensor or wiring fault

Checks & fixes (easiest first)

  1. Check coolant level (engine cool)
  2. Clean debris from radiator and coolers
  3. Verify fan engagement
  4. Compare sensor reading to an infrared thermometer
  5. Pressure-test the cooling system

FAQ

What does SPN 110 FMI 15 mean?

Engine Coolant Temperature — value too high (least severe). The reading is above normal, but only at the lowest warning level.

Is SPN 110 FMI 15 serious?

If the engine is truly overheating, stop and let it cool. Never open a hot radiator cap.

What should I check first for SPN 110 FMI 15?

Check coolant level (engine cool); Clean debris from radiator and coolers; Verify fan engagement.