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SPN 110 FMI 2

Engine Coolant Temperature — Data erratic, intermittent, or incorrect.
The signal jumps around, drops in and out, or disagrees with other information the controller has.

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

What FMI 2 usually points to: Loose or corroded connectors, chafed wiring, a failing sensor, or two redundant sensors that do not agree. More on FMI 2.

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 2 mean?

Engine Coolant Temperature — data erratic, intermittent, or incorrect. The signal jumps around, drops in and out, or disagrees with other information the controller has.

Is SPN 110 FMI 2 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 2?

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