P0388
Crankshaft Position Sensor B Circuit High
Ignition / engine position
Generic OBD-II
High
What it means
P0388 means the "B" crankshaft position sensor circuit is reading abnormally high. This sensor helps the ECM track crankshaft position for spark and fuel timing, so a bad signal can lead to rough running, stalling, or hard starting. It's a fault worth diagnosing promptly to avoid being stranded.
High
Can I keep driving? Potentially unreliable — the crankshaft sensor feeds engine timing, so you may get rough running, stalling, or a no-start. Have it diagnosed before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or intermittent stalling
- Engine misfires or hesitation
- Hard starting, or no-start in some cases
Common causes
Most likely first
- Failed crankshaft position sensor 'B'Likely
- Short to voltage or open in the sensor circuitCommon
- Damaged or corroded connector at the sensorCommon
- Reluctor-ring/tone-wheel damage or incorrect air gapLess often
- ECM fault (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and note whether the fault is constant or intermittent.
- Inspect the sensor connector and wiring for damage, chafing, or corrosion.
- Check the circuit for a short to voltage and confirm reference and ground.
- Verify the sensor air gap and inspect the reluctor ring for damage.
- Replace the 'B' crankshaft position sensor if it tests faulty; clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0388?+
Not recommended. A faulty crankshaft sensor can cause sudden stalling, so repair it before depending on the vehicle.
Can I just clear P0388?+
It returns once the ECM sees the high signal again. The sensor or wiring must be repaired first.
Related codes
Often seen with P0388
Read & clear P0388 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX