Code
P0386
GWM
P — Powertrain
- Incorrect indicator / not adjusted crankshaft position sensor B
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AI status
Completed
Completed
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Causes
- Incorrect sensor air gap or misadjusted mounting position
- Failed or degraded crankshaft position sensor B (Hall or inductive)
- Damaged/contaminated reluctor/trigger wheel or missing teeth
- Open/short/damaged wiring harness or poor connector contact
- Poor sensor ground or insufficient supply voltage
- Engine timing or reluctor-to-crankshaft phasing error
Symptoms
- MIL/Check Engine Light illuminated
- Hard starting or no-crank/no-start in some conditions
- Intermittent stalling or rough idle
- Misfires or uneven running under load
- Reduced engine performance or limp-home mode
- Diagnostic trouble codes related to crank/cam correlation
What to check
- Read and record freeze-frame and live PID data with a scan tool
- Verify battery voltage and charging system under cranking and running
- Visual inspection of sensor B connector, wiring harness, and pins
- Inspect reluctor/trigger wheel for missing/bent teeth, damage, or contamination
- Check sensor mounting for correct position and secure fastener
- Backprobe sensor supply and ground for correct voltages
Signal parameters
- Typical Hall-type: digital square wave 0–5 V (some systems 0–12 V) referenced to ground
- Typical inductive-type: AC sine/peaks, amplitude rises with engine speed (often 0.2–5 V AC at cranking; higher at rpm)
- Pulse frequency proportional to engine speed (pulses per crank rev depends on trigger wheel design)
- Steady, evenly spaced pulses with consistent amplitude; no missing pulses or dropouts
- Sensor resistance (for inductive sensors) often tens to hundreds of ohms — vehicle-specific; compare to spec
- Supply voltage to active sensors typically 5 V reference; ground near 0 V — check for deviations
Diagnostic algorithm
- Retrieve P0386 and any related codes (P0335/P0385/P0016 etc.), record freeze-frame, and clear the codes.
- Attempt to reproduce fault by monitoring live crank sensor B data during cranking and idle. Note irregularities or dropouts.
- Visually inspect sensor B, connector, and wiring for damage, corrosion, loose pins, or oil/debris contamination.
- Verify sensor supply voltage and ground at the connector with a multimeter (key ON, engine OFF). For active sensors, check reference (usually 5 V) and ground.
- Measure sensor output while cranking/running: use an oscilloscope for waveform and timing or a multimeter for AC voltage on inductive types. Look for consistent pulses and correct amplitude.
- Perform a wiggle test on wiring/connectors while monitoring the signal to reveal intermittent faults.
- Inspect the reluctor/trigger wheel for damaged or missing teeth, debris, or timing marks out of alignment. Check wheel-to-sensor air gap and reposition/adjust to spec if required.
- If sensor output is absent or out of spec, replace the sensor or repair wiring. If waveform is present but timing is incorrect, investigate mechanical timing (timing chain/belt/related components) or ECU correlation.
- After any repair or adjustment, clear codes, perform a crank/cam correlation relearn if required by the vehicle, and road test to confirm no recurrence.
- If fault persists after sensor and wiring repairs, consider ECU input circuit diagnosis or consult manufacturer technical data.
Likely causes
- Sensor B mounting bolt moved or incorrect shim/gap after service
- Sensor wiring rubbed through, shorted to ground, or intermittent
- Reluctor wheel damaged by debris or corrosion
- Connector corrosion causing high resistance or intermittent signal
- Sensor failed due to heat/age or internal short
- Crank timing belt/chain slipped causing correlation error
Fault status
Status
P0386 - Crankshaft Position Sensor B Incorrect Indicator / Not Adjusted (signal out of expected range or sensor mounting/gap incorrect).
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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