What it means
The turbocharger/supercharger bypass valve B reports a position sensor circuit/open condition. Boost recirculation cannot be commanded reliably on this branch.
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 B reports how far that branch's valve has moved. The control module sets P2C2A when the sensor signal circuit is open, so it cannot reliably confirm valve B position or manage boost recirculation.
Common causes
Most likely first.
- Open in sensor signal wire
- Position sensor failed
- Pin pushed back out of connector body
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 live bypass valve B command and position readings; check whether the position signal is absent or fixed.
- Inspect the valve B sensor connector for a pushed-back pin, poor latch, corrosion or a broken signal wire near the connector.
- Trace the sensor signal wire toward the control module and look for an open, chafed section or damaged splice in the valve B circuit.
- Using the manufacturer's wiring information, check signal-circuit continuity and connector terminal fit with power isolated as specified.
- If the wiring and terminals pass, test the valve B position sensor and its reference and ground circuits according to the manufacturer's procedure.
Common fixes
- Reconnect and secure a loose bypass valve B sensor connector or pushed-back pin.
- Repair an open or damaged valve B position-signal wire.
- Clean or replace a corroded connector terminal affecting the sensor circuit.
- Replace the bypass valve B position sensor if its circuit tests confirm sensor failure.
Can I keep driving?
If power is reduced or limp mode is active, drive gently and avoid demanding boost until valve position feedback is restored. Stop for severe power loss, heavy smoke or a strong misfire; unreliable boost control can worsen engine or emissions-system damage.
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.