P0387 code meaning
Crankshaft Position Sensor B Circuit Low
Powertrain system Generic code P03xx codes Check engine light
What P0387 means
By its J2012 name P0387 means the signal of the second crankshaft sensor stays at a low level – typically a short to ground of the signal wire, a missing or shorted sensor supply, or with an inductive sensor an amplitude that is too small. No manufacturer document available to us uses P0387: the engines with a sensor B that we found (GM Northstar 4.6 and 3.8-litre V6, the Honda 3.5-litre in the Saturn Vue Redline) report its electrical faults under P0385 and implausible signals under P0386. The description therefore follows the J2012 name, the function of sensor B and CARB's monitoring requirement for crank angle sensors. As long as sensor A works, the engine usually keeps running; together with a sensor A fault it may not start.
P0387 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0387
- Check engine light on
- Longer cranking
- Rough running, no start if sensor A also fails
Common causes of P0387
- Most likelySignal wire shorted to ground
- PossibleSensor faulty
- PossibleSensor supply too low or shorted
- Less likelyEngine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Crankshaft position sensor bCrankshaft tone wheelSensor wiringEngine control module
What each part of P0387 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| 87 | The exact fault in that area. |
What to do next
- Note P0387 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0387
What does P0387 mean?
P0387 means "Crankshaft Position Sensor B Circuit Low". By its J2012 name P0387 means the signal of the second crankshaft sensor stays at a low level – typically a short to ground of the signal wire, a missing or shorted sensor supply, or with an inductive sensor an amplitude that is too small. It is a generic code, so it means the same on every make.
Is it safe to drive with P0387?
Drive gently and only to a workshop. With P0387 the car can go into limp mode (reduced power) to protect itself.
Will P0387 fail an emissions test?
Yes, it can. P0387 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0387 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0387 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.