What it means
The position sensor reading does not transition cleanly between the two valve lift modes on bank 1. Sensor drift or mechanical wear leaves the signal between expected values.
At a glance
- Usually lights the check-engine light
How it works
The rocker arm actuator position sensor on bank 1 reports which of the engine’s two valve lift modes is engaged. The controller compares its signal with the expected positions as it commands a mode change; this code sets when the signal does not move into the expected range, suggesting drift or incomplete mechanical travel.
Common causes
Most likely first.
- Sensor signal drift after thermal aging
- Worn lock pin reduces travel between modes
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light
- Reduced engine power or acceleration
- Rough running or engine misfire
How to diagnose it
- Record freeze-frame data and compare the bank 1 position sensor reading with commanded lift mode in live data to see when the mismatch occurs.
- Check the bank 1 sensor connector and harness for heat damage, oil intrusion, loose pins, or corrosion that could distort the reading.
- With the engine off, inspect the bank 1 rocker arm actuator linkage for binding or signs that its lock pin cannot complete its travel.
- Use the scan tool’s actuator commands, if supported, to observe whether the bank 1 sensor reading reaches distinct expected positions in both modes.
- Test the sensor signal and its wiring through the full movement using the manufacturer’s procedure, then assess the actuator mechanism for wear if the circuit is sound.
Common fixes
- Repair a loose or damaged bank 1 sensor connector or harness.
- Replace the bank 1 rocker arm position sensor if its signal drifts outside the manufacturer’s specification.
- Repair or replace a worn bank 1 actuator lock pin or rocker mechanism that cannot travel fully.
- Replace the bank 1 actuator assembly if mechanical wear prevents reliable switching.
Can I keep driving?
If the engine runs smoothly and power is normal, limit driving to essential short trips and avoid hard acceleration. Stop if it misfires or loses power, since incomplete valve-mode switching can worsen drivability and may damage the engine.
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.