What it means
Position sensor A reports a value stuck near the low end of its travel even when the actuator is commanded to move. Either the actuator is mechanically stuck closed (wastegate jammed shut, VGT vanes seized at minimum opening) or the sensor itself is pegged low. Boost is uncontrolled — overboost on diesels with VGT, underboost on wastegate-stuck systems.
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 A reports the actuator's position so the control module can compare actual travel with its command. This code sets when the reading stays near the low end despite a request for movement, which can reflect a pegged sensor or an actuator or linkage stuck at that end; the resulting boost may be too low or, on some VGT systems, uncontrolled.
Common causes
Most likely first.
- Actuator mechanically stuck near low end
- Sensor pegged low
Symptoms
- Check-engine light may come on
- Reduced engine power or boost may occur
How to diagnose it
- Save freeze-frame data and compare commanded and actual sensor A position with boost pressure in live data to confirm the low reading persists when movement is requested.
- Inspect sensor A's connector and wiring for damage, poor contact, or contamination that could hold the signal low.
- Check the actuator rod and linkage for binding or signs that the wastegate or VGT mechanism is stuck near the low-travel end.
- Use the vehicle's supported actuator test, if available, and watch whether sensor A follows the command smoothly.
- Test sensor A's circuit and feedback against the manufacturer's specification to distinguish a sensor fault from mechanical binding.
Common fixes
- Repair a loose or damaged sensor A connector or wiring.
- Free or repair a binding actuator linkage using the manufacturer's service procedure.
- Replace sensor A if its feedback remains near the low end despite verified actuator movement.
- Repair or replace the actuator if it cannot move through its commanded range.
Can I keep driving?
Drive gently and avoid heavy acceleration or towing because boost may be reduced or poorly controlled. Stop if the engine loses substantial power, makes unusual turbo noises, 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.