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Diagnose/P0391
P0391High SeverityEngine

Camshaft Position Sensor B Circuit Range/Performance (Bank 1)

What This Means

The secondary camshaft position sensor B on bank 1 readings are outside the expected operating range. This sensor provides additional timing data for engines with dual overhead camshafts.

Common Symptoms

  • Hard starting
  • Rough idle
  • VVT malfunction
  • Check engine light on

Common Causes

  • Failed camshaft sensor B
  • Timing chain/belt wear
  • Wiring damage
  • Oil contamination
  • Connector issue

Estimated Repair Cost

$100 – $500
Parts and labor (varies by vehicle and location)
Difficulty:Moderate

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For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.