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SPN 651 FMI 2

Injector Cylinder #01 — 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: Circuit or performance fault for the cylinder 1 fuel injector. More on SPN 651.

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

Misfire and rough running are likely. Avoid heavy load; a stuck injector can damage the engine.

Likely causes

  1. Injector solenoid circuit open or shorted
  2. Damaged harness under the valve cover
  3. Worn or sticking injector
  4. ECM driver fault

Checks & fixes (easiest first)

  1. Run a cylinder cutout / contribution test
  2. Check injector circuit resistance
  3. Inspect harness under the valve cover
  4. Swap injector per OEM procedure if allowed

FAQ

What does SPN 651 FMI 2 mean?

Injector Cylinder #01 — data erratic, intermittent, or incorrect. The signal jumps around, drops in and out, or disagrees with other information the controller has.

Is SPN 651 FMI 2 serious?

Misfire and rough running are likely. Avoid heavy load; a stuck injector can damage the engine.

What should I check first for SPN 651 FMI 2?

Run a cylinder cutout / contribution test; Check injector circuit resistance; Inspect harness under the valve cover.