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2000 GMC SAVANA
4.3L V6•RWD•gas•L35
2 active safety recalls on this vehicle — view recalls
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Repairs0Labor505Torque139Fluid8DTC1763Battery1Maintenance0Recalls2
P1257high severityPowertrain

Supercharger System Overboost

on 2000 GMC Savana 4.3L V6 · RWD

What this code means

The supercharger is producing more boost pressure than commanded. This can be caused by a stuck bypass valve or boost control fault.

Symptoms

  • Reduced engine power
  • Check engine light on
  • Loss of performance

Common causes

  • Stuck supercharger bypass valve
  • Faulty boost pressure sensor
  • Bypass actuator failure
  • Vacuum line leak

Diagnostic steps

  1. Scan for boost-related codes
  2. Monitor boost pressure with scan tool
  3. Inspect bypass valve operation
  4. Check vacuum lines and actuator
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