P0387 Code: Crankshaft Position Sensor B Circuit Low
🟠 Moderate severity · drivable
If the engine is running, drive with caution — a failing crank sensor commonly causes stalling or a no-start.
What P0387 means
The crankshaft position sensor B circuit is reporting voltage that's too low. The computer can't read the sensor's signal correctly, which can mess up ignition and fuel timing.
Symptoms
- Check engine light is on
- Hard starting or no-start
- Engine stalling
- Rough running or misfiring
Common causes
- most common: Faulty crankshaft position sensor
- common: Wiring shorted to ground
- less common: Poor ground connection
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the crankshaft position sensor | Yes | $50–200 |
| Repair the shorted or grounded wiring | Mechanic | $50–200 |
Frequently asked questions
Can I drive with a P0387 code?
Only with caution, and only if the engine is running — a failing crank sensor often causes stalling or a no-start.
What is the most common cause of P0387?
A faulty crankshaft position sensor or wiring shorted to ground.
How much does it cost to fix a P0387?
Typically $50–$200 for a new crankshaft position sensor.
Related codes
P0385
P0385 Code: Crankshaft Position Sensor B Circuit Malfunction
P0388P0388 Code: Crankshaft Position Sensor B Circuit High
P0337P0337 Code: Crankshaft Position Sensor A Circuit Low Input
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.