What it means
The turbocharger/supercharger bypass valve B reports a position sensor circuit low 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 tells the control module how the valve is moving. P2C2B sets when the sensor signal voltage is below its expected range, commonly because the signal is shorted to ground or the sensor circuit has excessive resistance.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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
- Check freeze-frame and live valve B position data to confirm the reported signal is low and note the commanded valve position.
- Inspect bypass valve B sensor wiring and connector pins for corrosion, moisture, chafing or a signal wire touching ground.
- Using the manufacturer's wiring information, check sensor ground and reference circuits, then compare the signal reading with the manufacturer's specification.
- With power isolated as specified, test the signal wire for a short to ground and check for high resistance across connector terminals.
- If wiring and grounds pass, test the valve B position sensor response through the valve's travel using the manufacturer's procedure.
Common fixes
- Clean and secure corroded bypass valve B sensor connector pins.
- Repair a signal wire short to ground or damaged insulation in the valve B circuit.
- Repair poor sensor ground or reference connections if testing identifies them.
- Replace the valve B position sensor if its output remains low despite a sound circuit.
Can I keep driving?
With reduced power or limp mode, avoid hard acceleration and situations that require quick power until the valve feedback fault is fixed. Stop if the engine misfires severely, smoke increases or the warning light flashes, since unburned fuel can damage the catalytic converter.
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.