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SPN 110 FMI 16

Engine Coolant Temperature — Value too high (moderately severe).
The reading is above normal at a middle warning level — more serious than FMI 15, less than FMI 0.

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

What FMI 16 usually points to: A developing over-condition that often precedes a derate. More on FMI 16.

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 16 mean?

Engine Coolant Temperature — value too high (moderately severe). The reading is above normal at a middle warning level — more serious than FMI 15, less than FMI 0.

Is SPN 110 FMI 16 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 16?

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