What it means
Position sensor A signal voltage above the upper limit — short to reference voltage in the signal line or open signal return.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The turbocharger boost control position sensor A reports the position of the actuator that moves the turbo vanes or wastegate. The engine control module monitors its signal voltage, and this code sets when the signal is above the expected upper limit, such as when the signal wire is shorted to reference voltage or the signal return is open.
Common causes
Most likely first.
- Signal wire shorted to reference voltage
- Open signal return
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Reduced engine power or acceleration
- Poor boost response
How to diagnose it
- Use a scan tool to save freeze-frame data and compare sensor A's live position reading with the commanded turbo position to confirm the fault is present.
- Inspect sensor A's connector and harness for corrosion, loose or pushed-back pins, damaged insulation, and contact with reference-voltage wiring.
- Check the sensor ground or return path for continuity and excessive resistance using the vehicle wiring diagram and the manufacturer's specification.
- With the sensor connected, test the signal wire for an unintended connection to the reference-voltage circuit.
- If the wiring and return path pass, test sensor A and its supply and signal circuits against the manufacturer's specification before considering a control-module fault.
Common fixes
- Clean and secure corroded or loose sensor A connector pins.
- Repair a damaged signal wire shorted to reference voltage.
- Restore an open sensor return wire or connector terminal.
- Replace the position sensor or actuator assembly if it fails the specified circuit tests.
Can I keep driving?
Drive gently only if the vehicle responds normally; reduced power or poor boost can make merging and passing unsafe. Avoid heavy acceleration and have the fault checked soon, since incorrect boost control can worsen drivability and emissions.
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.