What it means
Position sensor B is electrically intact, but the reading does not track sensor A or the actuator-command model. Often a misaligned redundant sensor or aged element on a second turbo.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbo boost control uses an actuator to move a wastegate or variable vanes, while position sensor B reports actuator position for the engine control module to compare with sensor A or its commanded position. This code means sensor B's signal is present but does not agree with the expected position relationship. The module may reduce boost when it cannot reliably verify actuator movement.
Common causes
Most likely first.
- Sensor mounting misaligned after service
- Aged Hall element
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light on
- Reduced engine power or turbo boost
- Limp mode may occur
How to diagnose it
- Save freeze-frame data and graph live position readings from sensors A and B alongside the actuator command to identify when their tracking diverges.
- Inspect sensor B's mounting and linkage for looseness, incorrect position, or signs that it was disturbed during turbo or actuator service.
- Check the sensor B connector and harness for damage or poor contact that could make a valid signal unstable.
- Command the boost actuator through its range with a suitable scan tool and observe whether sensor B follows smoothly and consistently relative to sensor A.
- If alignment and wiring are sound, test sensor B and the actuator against the manufacturer's procedure before replacing either.
Common fixes
- Secure and correctly align sensor B if its mounting has shifted.
- Repair a damaged connector or harness affecting sensor B.
- Replace a sensor B element that gives a consistently out-of-range position reading.
- Repair or replace a sticking actuator if it fails to move in step with the command.
Can I keep driving?
Limit acceleration and avoid towing or sustained high-load driving while boost is reduced or inconsistent. Continued driving can bring on a protective power limit, and an actuator fault may worsen.
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.