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SPN 190 FMI 2

Engine Speed — 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: Engine RPM, usually calculated from the crankshaft and/or camshaft position sensors. More on SPN 190.

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

HIGH — limit use, diagnose now

An overspeed or lost speed signal can cause stalling or engine damage. Investigate before running.

Likely causes

  1. Overspeed (downhill in too low a gear, runaway)
  2. Crank or cam sensor fault
  3. Damaged tone wheel
  4. Wiring or connector issue

Checks & fixes (easiest first)

  1. Check whether the fault logged during an actual overspeed
  2. Inspect crank and cam sensors and connectors
  3. Check SPN 636/637 codes
  4. Verify sensor air gap and tone wheel condition

FAQ

What does SPN 190 FMI 2 mean?

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

Is SPN 190 FMI 2 serious?

An overspeed or lost speed signal can cause stalling or engine damage. Investigate before running.

What should I check first for SPN 190 FMI 2?

Check whether the fault logged during an actual overspeed; Inspect crank and cam sensors and connectors; Check SPN 636/637 codes.