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P257C Powertrain

Vacuum Reservoir Control Circuit High

The vacuum reservoir control circuit reads stuck high — short to battery voltage or open coil. The driver cannot pull the line low to actuate the valve/motor.

Affected components

  • Vacuum reservoir control valve

Common causes

  • High likelihood: Control wire shorted to battery voltage
  • Medium likelihood: Open coil
  • Low likelihood: Connector pins corroded - high contact resistance

Diagnostic notes

  • The malfunction indicator lamp may illuminate

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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