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P0391 Powertrain

Camshaft Position Sensor B Circuit Range/Performance (Bank 2)

Cam sensor B on bank 2 reads in range but plausibility check fails — slow response, drift, or signal does not match expected cam profile.

Affected components

  • Camshaft position sensor

Common causes

  • High likelihood: Sensor drift
  • Low likelihood: Sensor element aged beyond calibration window
  • Low likelihood: Sensor mounting loose - signal damping

Possible symptoms

  • Check engine light on
  • Power loss especially in mid-rpm range
  • Possible rough idle or stalling
  • Increased fuel consumption

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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