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SPN 105 FMI 2

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

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

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 2 mean?

Intake Manifold #1 Temperature — data erratic, intermittent, or incorrect. The signal jumps around, drops in and out, or disagrees with other information the controller has.

Is SPN 105 FMI 2 serious?

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

What should I check first for SPN 105 FMI 2?

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