What it means
Same condition as the A-side stuck-low fault, but on the second sensor / second turbo. Position sensor B reads stuck near the low end while the actuator is commanded.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbocharger boost control position sensor B reports actuator travel to the control module, which compares it with the requested position. This code sets when sensor B remains near the low end despite a movement command, indicating a low-pegged or misadjusted sensor, wiring trouble, or a B-side actuator or linkage stuck near that end; sensor B does not by itself prove the vehicle has a second turbo.
Common causes
Most likely first.
- Boost-control actuator or linkage binding near the low-travel end
- Position sensor B misadjusted or reporting incorrectly
- Damaged actuator wiring or connector
Symptoms
- Check-engine light may come on
- Reduced engine power or boost may occur
How to diagnose it
- Record freeze-frame data and compare commanded and actual sensor B position with boost pressure in live data to confirm the low reading occurs when movement is requested.
- Inspect sensor B's connector and wiring for loose terminals, corrosion, damage, or contamination that could distort feedback.
- Check the B-side actuator rod and linkage for binding near the low-travel end.
- Use a supported actuator test, if available, and watch whether sensor B follows the requested movement.
- Test sensor B's circuit and adjustment against the manufacturer's specification before replacing the sensor or actuator.
Common fixes
- Repair damaged wiring or poor contact at sensor B.
- Correct sensor B adjustment according to the manufacturer's procedure.
- Free or repair a binding B-side actuator linkage.
- Replace sensor B or its actuator if testing confirms it cannot report or reach the commanded position.
Can I keep driving?
Drive gently and avoid heavy acceleration or towing because the B-side boost control may be limited or unstable. Stop if the engine loses substantial power, develops unusual turbo noise, or produces heavy smoke.
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.