P0385 medium Severity

P0385: Crankshaft Position Sensor B Circuit Malfunction

May cause rough idle, stalling, hard starting or no-start depending on vehicle and how sensor data is used by PCM

Overview

P0385 indicates a malfunction in the crankshaft position sensor ‘B’ circuit where the PCM/ECM does not detect a valid signal from the CKP ‘B’ sensor impacting engine timing and performance

Common Symptoms

  • Check Engine Light illuminated
  • Difficulty starting engine or no start
  • Rough idle or misfire
  • Engine stalling or hesitation
  • Reduced performance

Most Common Causes

Faulty crankshaft position sensor B high

Sensor internal failure or worn out sensor failing to provide correct signal

Wiring harness/connector damage or corrosion high

Broken wires, corroded connector pins or loose connections disrupting signal

Reluctor/tone ring damage or misalignment medium

Physical damage to the reluctor wheel can interrupt correct sensor readings

ECM/PCM fault low

Control module may misinterpret or fail to receive signal after other causes ruled out

Diagnostic Steps

  1. Connect an OBD-II scan tool and confirm P0385 and any related codes
    Expected: P0385 present; note any additional codes like P0386–P0389 or P0335 series
    Interpretation: Confirms crankshaft B circuit issue and detects other potentially related circuits
  2. Visually inspect CKP sensor B wiring and connector for damage, corrosion or loose pins
    Expected: No broken wires/corrosion; secure connections
    Interpretation: If damaged, repair wiring/connectors and retest
  3. Measure sensor output with multimeter/oscilloscope while cranking engine
    Expected: Valid waveform or resistance per OEM specification
    Interpretation: Invalid signal suggests sensor or circuit failure
  4. Check continuity of wiring between sensor and PCM for open/shorts
    Expected: Continuous circuit with no shorts
    Interpretation: Continuity failures indicate wiring repair needed
  5. Inspect reluctor ring/trigger wheel for missing teeth, misalignment or damage
    Expected: Uniform teeth and alignment
    Interpretation: Damage here can cause intermittent or missing signal
  6. If all above are good, consider ECM/PCM testing per manufacturer procedures
    Expected: ECM recognizes valid signal
    Interpretation: If not, ECM repair or reprogramming may be required

Repair Solutions

Replace crankshaft position sensor B medium
Estimated Cost: $50 - $300

Typical fix if sensor itself is faulty; cost varies by vehicle

Repair or replace damaged wiring/connectors medium
Estimated Cost: $20 - $150

Repair broken wires, improve connections and apply dielectric grease

Replace damaged reluctor ring/trigger wheel hard
Estimated Cost: $150 - $600

Involves mechanical engine work

ECM/PCM reprogramming or replacement hard
Estimated Cost: $500 - $2000

Rare and should be last option after ruling out all wiring and sensor faults

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Confusing P0385 with P0335 (Crankshaft Position Sensor A Circuit)
  • Replacing sensor without checking wiring harness/connectors
  • Assuming rough idle is caused solely by ignition or fuel system

Frequently Asked Questions

What does a P0385 diagnostic trouble code signify?

The P0385 code stands for Crankshaft Position Sensor B Circuit Malfunction. This generally indicates an issue with the Sensors system.

Can P0385 cause engine damage?

With a severity level of medium, may cause rough idle, stalling, hard starting or no-start depending on vehicle and how sensor data is used by PCM

How do I know if I have code P0385?

Common symptoms include: Check Engine Light illuminated, Difficulty starting engine or no start, Rough idle or misfire. You might also notice the Check Engine Light is on.

Why is my car throwing a P0385 code?

The most common causes are: Faulty crankshaft position sensor B, Wiring harness/connector damage or corrosion, Reluctor/tone ring damage or misalignment.

What is the price difference for fixing P0385?

Repair costs depend on the specific failure. A simple Repair or replace damaged wiring/connectors replacement is relatively affordable ($20-$150), whereas a ECM/PCM reprogramming or replacement repair is more expensive, potentially reaching $2000.

Does P0385 affect Ford, Toyota, or Honda?

Yes, P0385 is a generic code that applies to all OBD-II compliant vehicles, including Ford, Toyota, Honda, Chevrolet, Nissan, Dodge, BMW, and more.

User Comments (0)

Share your experience or ask a question about this code.

Be the first to share your experience with P0385!