Home › Codes › SPN 641 › FMI 2

SPN 641 FMI 2

VGT Actuator — 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: The electronic actuator that moves the vanes in a variable-geometry turbocharger. More on SPN 641.

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

Expect low power and possibly a derate. Drivable carefully.

Likely causes

  1. Sticking VGT vanes (soot/carbon)
  2. Failed actuator motor or internal electronics
  3. Overheated actuator
  4. Wiring or power supply issue

Checks & fixes (easiest first)

  1. Run the OEM VGT sweep/calibration test
  2. Check actuator power and ground
  3. Inspect the turbo for vane sticking
  4. Check boost codes

FAQ

What does SPN 641 FMI 2 mean?

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

Is SPN 641 FMI 2 serious?

Expect low power and possibly a derate. Drivable carefully.

What should I check first for SPN 641 FMI 2?

Run the OEM VGT sweep/calibration test; Check actuator power and ground; Inspect the turbo for vane sticking.