Powertrain, generic · Ignition system or misfire

P0387 Crankshaft Position Sensor B Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Signal wire shorted to ground
Sensor faulty
Sensor supply too low or shorted
Engine module

Symptoms

  • Check engine light on
  • Longer cranking
  • Rough running, no start if sensor A also fails

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–350
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

crankshaft position sensor bcrankshaft tone wheelsensor wiringengine control module

Related codes

P0385P0386P0337P0335

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.