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SPN 108 FMI 2

Barometric Pressure — 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: Outside air pressure, used to correct fueling and boost for altitude. More on SPN 108.

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

LOW — usually OK to keep running

Usually a minor drivability issue, but get it fixed so boost and fueling stay accurate.

Likely causes

  1. Faulty barometric sensor (often inside the ECM)
  2. Wiring fault on external sensors
  3. ECM internal fault

Checks & fixes (easiest first)

  1. Compare reading to local barometric pressure
  2. Inspect wiring on external sensors
  3. Check for ECM supply voltage codes

FAQ

What does SPN 108 FMI 2 mean?

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

Is SPN 108 FMI 2 serious?

Usually a minor drivability issue, but get it fixed so boost and fueling stay accurate.

What should I check first for SPN 108 FMI 2?

Compare reading to local barometric pressure; Inspect wiring on external sensors; Check for ECM supply voltage codes.