Quick answer: The P0385 code indicates a circuit malfunction in the secondary crankshaft position sensor (Sensor B). This critical sensor feeds position and engine speed data to the engine control module to manage ignition timing and fuel injection. Vehicle operation is affected severely, making immediate diagnosis essential to prevent sudden engine stalling.
Seeing code P0385 pop up on your diagnostic tool usually comes alongside engine performance issues or a sudden engine stall. This guide explains what Sensor B does, how to identify the underlying problem, and how much you should expect to pay for repairs.
What Does P0385 Mean?
Your engine relies on crankshaft position sensors to track the precise position and rotational speed of the crankshaft. Modern engines often use two sensors-designated as Sensor A and Sensor B-for added accuracy and engine timing precision. Code P0385 triggers when the Engine Control Module (ECM) detects a missing, intermittent, or irregular voltage signal from the Sensor B circuit. Without accurate data from this sensor, the engine management computer cannot correctly time ignition spark or fuel delivery.
Symptoms
- Engine stalling while driving or sitting at a red light
- Engine cranking over continuously but failing to start
- Misfiring, rough idling, or engine hesitation under load
- Noticeable loss of engine power and poor acceleration
- Illuminated Check Engine Light on the dashboard
Possible Causes
Replacing the sensor immediately is a common mistake; electrical issues in the wiring harness are frequently the real culprit.
- Damaged, burned, or shorted wiring in the Sensor B circuit
- Corroded or loose electrical plug at the sensor or PCM connection
- Faulty crankshaft position sensor B
- Damaged or cracked reluctor ring teeth on the crankshaft
- Failed Powertrain Control Module (rare)
Check These Yourself Before Visiting a Mechanic
- Inspect the Sensor B wiring harness for visible damage, melting, or chafing against metal engine components.
- Disconnect the sensor plug to check for green corrosion, dirt contamination, or bent metal pins.
- Check battery health and terminals, as low system voltage can cause false sensor circuit fault codes.
How to Fix It
- Scan the vehicle for secondary diagnostic codes that might pinpoint voltage issues or related sensor faults.
- Perform a thorough visual inspection of the Sensor B harness, connector, and frame grounds.
- Test circuit reference voltage, ground, and signal wires at the sensor plug using a digital multimeter.
- Inspect the sensor’s signal output using an oscilloscope or live scan tool data to confirm component failure.
- Replace Crankshaft Position Sensor B if circuit wiring is intact but signal output is dead or erratic.
- Inspect the internal reluctor ring through the mounting hole if a new sensor fails to restore signal.
Estimated Repair Costs (2026)
| Job | Parts ($) | Labor ($) |
|---|---|---|
| Wiring Repair / Connector Fix | $15 – $45 | $75 – $150 |
| Crankshaft Position Sensor B Replacement | $35 – $110 | $80 – $160 |
| Reluctor Ring Replacement | $45 – $130 | $250 – $500 |
| Diagnostic Fee | $0 | $80 – $150 |
Note: these are 2026 estimates in US dollars; costs vary by make and model.
Frequently Asked Questions
Can I drive with the P0385 code?
It is not advisable to drive with code P0385 active. The engine can cut out completely without warning, which creates a dangerous driving situation in heavy traffic or at high speeds.
How do I clear the P0385 code?
You can clear the code using an OBD-II scanner after repairing the underlying circuit or replacing the failed sensor. The light may also turn off automatically after completing several successful driving cycles without detected errors.
Does P0385 mean my engine is permanently damaged?
No, P0385 indicates an electrical signal issue rather than mechanical destruction. Repairing the sensor or wiring will restore normal engine functionality without permanent harm to your vehicle.