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P0387 Crankshaft Position Sensor B Circuit Low Input

The OBD2 code P0387 indicates that the Crankshaft Position Sensor B is providing a low voltage input signal, which may suggest a malfunction in the sensor or its circuit

Definition

The OBD2 code P0387 indicates that the Crankshaft Position Sensor B is providing a low voltage input signal, which may suggest a malfunction in the sensor or its circuit

Common causes

  • Faulty crankshaft position sensor
  • Damaged wiring or connectors
  • Poor electrical connections
  • Faulty engine control module (ECM)
  • Timing belt or chain issues
  • Oil contamination on the sensor
  • Incorrect sensor installation or alignment

Common misdiagnoses

  • Faulty crankshaft position sensor
  • Faulty camshaft position sensor
  • Wiring issues or shorts in the sensor circuit
  • Faulty engine control module (ECM)
  • Timing belt or chain issues
  • Fuel delivery problems
  • Ignition system faults
  • Battery or charging system issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect the Crankshaft Position Sensor

    Locate the crankshaft position sensor (CKP) and visually inspect it for any signs of damage, corrosion, or loose connections

  3. 3. Ensure that the sensor is properly mounted and that there are no obstructions

  4. 4. Check Wiring and Connectors

    Inspect the wiring harness and connectors leading to the crankshaft position sensor for any signs of wear, fraying, or damage

  5. 5. Look for any loose or corroded connections that could affect the signal

  6. 6. Test the Crankshaft Position Sensor

    Use a multimeter to test the resistance of the crankshaft position sensor. Compare the readings to the specifications provided in the vehicle’s service manual

  7. 7. If the sensor is faulty, it may need to be replaced

  8. 8. Check Power and Ground

    Verify that the crankshaft position sensor is receiving the correct voltage and ground. Use a multimeter to check for power at the sensor connector

  9. 9. If there is no power or ground, trace the wiring back to the engine control module (ECM) to identify any breaks or shorts

  10. 10. Inspect the Engine Control Module (ECM)

    If all other components check out, the issue may lie with the ECM. Ensure that the ECM is functioning properly and that there are no internal faults

  11. 11. Check for any software updates or recalls related to the ECM

  12. 12. Check for Mechanical Issues

    Inspect the engine for any mechanical issues that could affect the crankshaft position sensor, such as a damaged crankshaft or timing belt/chain problems

  13. 13. Clear Codes and Test Drive

    After performing repairs or replacements, clear the trouble codes using the OBD-II scanner

  14. 14. Take the vehicle for a test drive to see if the code returns. Monitor the engine performance during the drive

  15. 15. Consult a Professional

    If the issue persists after following these steps, it may be best to consult a professional mechanic for further diagnosis and repair.Additional Tips: - Always refer to the vehicle’s service manual for specific testing procedures and specifications. - Ensure that you are working in a safe environment and take necessary precautions when working on the vehicle. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0387 code