What it means
The rocker arm actuator B on bank 1 is commanded to engage but does not switch. Engine stays in the wrong lift or cylinder mode under load.
At a glance
- Usually lights the check-engine light
How it works
The B rocker arm actuator on bank 1 moves the valve mechanism into its alternate lift mode, using engine oil pressure to help operate the mechanism. This code sets when the controller commands actuator B on but the mechanism remains off, which can result from low oil pressure, a stuck lock pin, or restricted movement.
Common causes
Most likely first.
- Low oil pressure cannot move the actuator
- Mechanical lock pin stuck in unactivated position
- Carbon or debris buildup preventing free movement
Symptoms
- Check-engine light
- Reduced engine power or acceleration
- Rough running or engine misfire
How to diagnose it
- Record freeze-frame data and compare commanded bank 1 B actuator state with available position or lift-mode data to confirm it fails to engage.
- Check the engine oil level and condition first, since low or degraded oil can prevent the bank 1 actuator from moving correctly.
- Inspect the bank 1 B actuator connector and oil control valve area for wiring damage, leaks, or debris.
- Use a scan tool to command the bank 1 B actuator and observe whether its position or engine response changes as expected.
- If oil and electrical controls are sound, inspect the B actuator lock pin and rocker mechanism for sticking or deposits using the manufacturer’s procedure.
Common fixes
- Correct the engine oil level and use the specified oil if the level or condition is unsuitable.
- Repair a damaged connector or wiring fault at the bank 1 B actuator.
- Clean or replace a restricted bank 1 B oil control valve if testing confirms it is sticking.
- Repair or replace the bank 1 B lock pin or rocker mechanism if it is mechanically stuck off.
Can I keep driving?
Avoid hard acceleration and heavy loads because bank 1 may not switch to the commanded lift mode and power can be reduced. Stop if the engine misfires badly, oil pressure warning appears, or abnormal mechanical noise develops.
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.