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P25B4 Powertrain

Turbocharger/Supercharger Wastegate A Stuck Closed

Wastegate A is mechanically stuck closed. The turbo cannot bleed off exhaust at high load — boost overshoots the setpoint, risking overboost cut-off and damage to the turbo bearing. Carbon-locked flap, seized linkage or aged actuator are typical causes.

Affected components

  • Wastegate a
  • Turbocharger a

Common causes

  • High likelihood: Carbon-locked wastegate flap
  • Medium likelihood: Seized linkage
  • Low likelihood: Carbon or debris buildup preventing free movement

Possible symptoms

  • Check engine light on
  • Significant power loss / limp mode
  • Possible blue or black smoke from exhaust
  • Whistling or hissing sound from intake

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions

Related codes

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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