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P0388 Powertrain

Crankshaft Position Sensor B Circuit High

Crank sensor B above upper plausibility — open signal or short to B+. The crankshaft position sensor provides RPM and crank angle — without a valid signal, no ignition and no injection. Engine will not start or stalls instantly.

Affected components

  • Crankshaft position sensor

Common causes

  • High likelihood: Open signal line
  • Low likelihood: Connector pins corroded - high contact resistance
  • Low likelihood: Supply wire pinched against B+ source

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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