Crankshaft Position Sensor B Circuit Intermittent
The P0389 code indicates that the Engine Control Module (ECM) has detected an intermittent or erratic signal from the crankshaft position sensor B circuit. This sensor is critical for engine timing and fuel injection synchronization. An intermittent signal can cause misfires, stalling, or no-start conditions. Common causes include a faulty sensor, damaged wiring, poor electrical connections, or issues with the reluctor wheel.
01. Most Common Causes
- Faulty crankshaft position sensor B
- Damaged or corroded wiring/connectors
- Intermittent short or open in the circuit
- Damaged reluctor wheel or excessive air gap
02. Symptoms You Will Notice
- Engine cranks but does not start
- Intermittent stalling or rough idle
- Check Engine Light illuminated
- Engine misfire or hesitation during acceleration
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the sensor and wiring for damage, corrosion, or loose connections.
Step 3: Test sensor resistance and signal output with a multimeter or oscilloscope.
Step 4: Check the reluctor wheel for damage or debris and verify proper air gap.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may stall unexpectedly or fail to start, posing a safety risk.
How much does it cost to fix?▼
Typically $50-$150 for a DIY sensor replacement; labor at a shop may add $100-$200.