What it means
The turbocharger/supercharger bypass valve A reports a position sensor circuit high condition. Boost recirculation cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The position sensor on turbocharger or supercharger bypass valve A reports the valve's position so the control module can manage boost recirculation. This code sets when the sensor signal is abnormally high, which can be caused by a signal wire short to battery voltage, an open sensor, or poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open position sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Record freeze-frame data and compare commanded bypass valve A position with live position feedback, if available; look for a high, fixed, or implausible reading.
- Inspect the valve A sensor connector and harness for a disconnected plug, corrosion, damaged pins, or chafing against a power wire.
- Check the sensor wiring for an open circuit or a signal wire shorted to battery voltage.
- Use the wiring diagram to test the sensor supply, ground, and signal circuits according to the manufacturer's procedure.
- If the harness and connections pass, test the valve A position sensor and replace it if it is open or faulty.
Common fixes
- Reconnect the valve A sensor or clean and repair its connector terminals.
- Repair an open or damaged position-sensor wire.
- Repair the signal wire if it is shorted to a power feed.
- Replace the bypass valve A position sensor or valve assembly if testing confirms it is faulty.
Can I keep driving?
Avoid hard acceleration, towing, and high-speed driving if the vehicle has reduced power or limp mode. The control module cannot reliably track bypass valve A position, so boost response may be impaired.
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.