What it means
The signal from crankshaft position sensor B is intermittent or erratic. The effect on engine operation depends on how the vehicle uses this sensor.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Crankshaft position sensor B supplies engine-position information that the controller needs to manage engine operation. This code sets when sensor B's signal drops out or varies unpredictably, often because a connector or wire loses contact as the engine vibrates.
Common causes
Most likely first.
- Intermittent connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light on
- Intermittent hard starting or no-start
- Engine may stall or run unevenly
- Reduced engine performance
How to diagnose it
- Review freeze-frame data and live engine-speed or sensor B data for dropouts, especially around the time of a stall or rough-running event.
- Inspect sensor B's connector for loose, corroded, or damaged terminals and check that it locks securely.
- Trace the harness for chafing or contact with vibrating or moving parts, then gently move accessible sections while watching live data.
- Check sensor mounting and the visible tone wheel for looseness, damage, or debris that could make the signal unstable.
- If the connection and harness are sound, test sensor B's signal during cranking and running against the manufacturer's procedure.
Common fixes
- Secure a loose sensor B connector or repair terminals with intermittent contact.
- Reroute and secure harness sections rubbing against vibrating components.
- Repair damaged wiring or a loose sensor mounting.
- Replace sensor B if its signal remains intermittent with a sound connection and harness.
Can I keep driving?
Because the fault can come and go, the engine may stall or lose power without warning. Avoid driving if stalling has occurred, and do not rely on the vehicle for a trip where an unexpected stop would be unsafe.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.