Engine

P0386 — Crankshaft Position Sensor B Circuit Range/Performance

Severity: medium Drive with care, to a shop

What P0386 means

The engine control module monitors the secondary crankshaft position sensor (sensor B), which reads a toothed wheel on the crankshaft to determine engine speed and position. This data is used to time ignition and fuel injection. P0386 sets when the signal is erratic, drops out or falls outside the expected range.

Symptoms

  • Check Engine light on
  • Rough idle
  • Intermittent misfires
  • Engine stalling
  • Hard or long cranking before starting
  • Reduced power and sluggish acceleration

Possible causes

  1. Failed crankshaft position sensor B
  2. Damaged, corroded or loose wiring and connectors in the sensor circuit
  3. Damaged or dirty tone (reluctor) wheel on the crankshaft
  4. Loose sensor or incorrect air gap
  5. Faulty engine control module (rare)

How to diagnose

  1. Scan for all codes and freeze frame data, noting related camshaft sensor or misfire codes.
  2. Inspect the sensor, harness and connector for chafing, oil contamination and corroded pins.
  3. Check that the sensor is securely mounted with no play and that its seal is intact.
  4. Measure sensor resistance and verify power and ground against the factory wiring diagram.
  5. Test the wiring for opens and shorts to ground or power, wiggling the harness with the engine running.
  6. Compare the sensor B waveform on a scope with the primary crankshaft and camshaft sensor signals.
  7. Inspect the tone wheel for damaged or debris-filled teeth where accessible.
  8. Suspect the control module only after everything else checks out.

Common fixes

  • Replace crankshaft position sensor B
  • Repair or replace damaged wiring and connectors
  • Replace or repair the tone wheel
  • Correct sensor mounting and air gap
  • Replace or reprogram the control module if confirmed faulty

Questions and answers

What does P0386 mean?

The control module found that the crankshaft position sensor B signal is out of range or behaving incorrectly. The cause may be the sensor, its wiring or the tone wheel.

Can I drive with P0386?

Only a short distance and carefully, for example to a shop. The engine may stall or not restart, so don't put off the repair.

Will replacing the sensor fix it?

Not always. Check the wiring, connector, mounting and tone wheel first, or the code may return after the new sensor is installed.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.