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SPN 105 FMI 16

Intake Manifold #1 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 air entering the cylinders after the charge air cooler. More on SPN 105.

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

Severity

MEDIUM — fix soon

High intake temps reduce power and can lead to a derate. Drivable with care.

Likely causes

  1. Dirty or blocked charge-air cooler fins
  2. Charge-air cooler leak
  3. Fan not engaging
  4. EGR cooler problem raising intake temperature
  5. Sensor or wiring fault

Checks & fixes (easiest first)

  1. Clean the CAC and radiator stack
  2. Verify fan engagement
  3. Pressure-test the CAC
  4. Compare the sensor to ambient after a cold soak

FAQ

What does SPN 105 FMI 16 mean?

Intake Manifold #1 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 105 FMI 16 serious?

High intake temps reduce power and can lead to a derate. Drivable with care.

What should I check first for SPN 105 FMI 16?

Clean the CAC and radiator stack; Verify fan engagement; Pressure-test the CAC.