What it means
The third bypass valve current does not match the commanded value within tolerance. Drifted coil resistance or high-resistance contact in the connector.
At a glance
- Usually lights the check-engine light
How it works
Bypass valve C is the third bypass valve in the turbocharger or supercharger air-bypass system. The control module compares the current through its valve circuit with the commanded value and sets this code when they do not track within the expected range, which can point to a drifting coil or a resistive connection.
Common causes
Most likely first.
- Coil resistance changed by thermal stress
- High-resistance contact in the valve connector
- Sensor element aged beyond calibration window
Symptoms
- Reduced engine power or boost
- Sluggish acceleration
- Check-engine light may illuminate
How to diagnose it
- Read freeze-frame data and compare commanded valve C operation with available circuit-current or actuator data to see when the mismatch occurred.
- Inspect valve C's connector and wiring for loose, corroded, heat-damaged, or strained contacts that could add resistance.
- Check the valve C coil and its connector contacts for resistance or voltage drop, comparing results with the manufacturer's specification.
- Use a scan tool's actuator test, if supported, to command valve C and observe whether its electrical response follows the command.
- If the wiring and valve check out, investigate the control module's driver and related data before replacing parts.
Common fixes
- Clean and secure corroded or loose valve C connector contacts.
- Repair damaged wiring or a poor connection in the valve C circuit.
- Replace bypass valve C if its coil resistance is outside the manufacturer's specification.
- Repair the control module driver only after confirming the valve and circuit are sound.
Can I keep driving?
If power and boost feel normal and no temperature warning appears, a short, gentle trip may be possible, but avoid hard acceleration or towing. Reduced boost can worsen, so stop if power drops sharply or another warning appears.
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.