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SPN 641 FMI 7

VGT Actuator — Mechanical system not responding or out of adjustment.
The controller commanded something to move or change, and the result did not match the command.

What the SPN covers: The electronic actuator that moves the vanes in a variable-geometry turbocharger. More on SPN 641.

What FMI 7 usually points to: Stuck or sticking valve or actuator, binding linkage, carbon buildup, or a component worn out of adjustment. More on FMI 7.

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 7 mean?

VGT Actuator — mechanical system not responding or out of adjustment. The controller commanded something to move or change, and the result did not match the command.

Is SPN 641 FMI 7 serious?

Expect low power and possibly a derate. Drivable carefully.

What should I check first for SPN 641 FMI 7?

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