John Deere Fault Code
Free · no signupSPN 641 FMI 5
Low Boost / Black Smoke
System
Turbo
Symptom
Low Boost / Black Smoke
Diagnosis & fix steps
LOGIC: Variable Geometry Turbocharger (VGT) Actuator Circuit Has High Resistance.
ACTION: Check the power and ground pins at the smart actuator. Look for corrosion inside the connector plug.
Red Seal field insights
Red Seal Logic: High resistance indicates a loose terminal, a frayed wire, or an open coil inside the electric VGT stepper motor.
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