What it means
The position sensor signal for actuator B on bank 1 jumps or drops out intermittently. Usually a loose connector or a chafed wire.
At a glance
- Usually lights the check-engine light
How it works
The B rocker arm actuator position sensor tracks the switching state on bank 1. This intermittent/erratic code sets when the signal drops out or jumps unpredictably, so the controller cannot reliably confirm the actuator's position.
Common causes
Most likely first.
- Sensor connector not fully seated
- Harness chafed against valve cover
- Connector with intermittent contact under vibration
Symptoms
- Check-engine light
- Intermittent loss of power or acceleration
- Rough running or engine misfire
How to diagnose it
- Record freeze-frame data and review live bank 1 B position data to see whether dropouts coincide with vibration, temperature, or actuator commands.
- Inspect the sensor connector and harness near the valve cover for a loose plug, chafing, or damaged insulation.
- With live data displayed, gently wiggle the connector and harness to reproduce a dropout and narrow down its location.
- Check connector pin fit and test the sensor wiring for intermittent continuity using the manufacturer's procedure.
- If the wiring remains stable, test the B position sensor through its operating range against the manufacturer's specification.
Common fixes
- Fully seat and secure the bank 1 B sensor connector.
- Repair chafed wiring near the valve cover and secure the harness away from rubbing points.
- Replace damaged connector terminals that lose contact under vibration.
- Replace the B position sensor if its output remains erratic with sound wiring.
Can I keep driving?
Drive cautiously and avoid hard acceleration while power or sensor readings are intermittent; the engine may run roughly or lose power unexpectedly. Stop if misfiring becomes severe or the check-engine light flashes.
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.