Faulty bypass valve solenoid or actuator; Sticking or seized bypass valve mechanism due to carbon buildup or corrosion; Damaged or disconnected vacuum line to the bypass valve; Wiring harness damage (open, short, or chafed wires) to the bypass valve; Corroded or loose electrical connector at the bypass valve; Failed powertrain control module (rare)

DTC codes / P2Cxx · Hybrid propulsion / P2C29

P2C29Turbocharger/Supercharger Bypass Valve B Stuck

Q: What does code P2C29 mean?

Turbocharger/Supercharger Bypass Valve B Stuck. P2C29 indicates that the powertrain control module has detected a fault with the 'B' bypass valve circuit for a turbocharger or supercharger, where the valve is reported as stuck. The computer monitors the valve's electrical circuit and/or position feedback and sets this code when the commanded state does not match the actual state, or when the circuit indicates a stuck condition.

P2C29 indicates that the powertrain control module has detected a fault with the 'B' bypass valve circuit for a turbocharger or supercharger, where the valve is reported as stuck. The computer monitors the valve's electrical circuit and/or position feedback and sets this code when the commanded state does not match the actual state, or when the circuit indicates a stuck condition.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine power or limp mode under acceleration
Poor fuel economy or rich-running conditions
Rough idle or stalling after deceleration
Audible hissing or whistling from the engine bay during boost
Delayed or harsh turbocharger response

Common causes, most likely first

Faulty bypass valve solenoid or actuator
Sticking or seized bypass valve mechanism due to carbon buildup or corrosion
Damaged or disconnected vacuum line to the bypass valve
Wiring harness damage (open, short, or chafed wires) to the bypass valve
Corroded or loose electrical connector at the bypass valve
Failed powertrain control module (rare)

How to diagnose and fix it

Connect a scan tool and verify the code is current, then command the bypass valve open and closed to observe operation and listen for movement.
Inspect the vacuum lines and electrical connector at the bypass valve for cracks, disconnection, or corrosion; repair or replace as needed.
Measure resistance and voltage on the bypass valve control circuit and compare to manufacturer specifications to rule out wiring faults.
Remove the bypass valve and inspect for carbon buildup or mechanical binding; clean or replace the valve if it does not move freely.
Test the bypass valve solenoid with a known-good unit or apply direct power to confirm actuation.
If all electrical and mechanical checks pass, consult factory service information for pinpoint tests specific to the vehicle before replacing the PCM.

Don't overlook the simple mechanical checks

A stuck bypass valve is often caused by carbon deposits rather than an electrical failure, so cleaning the valve can resolve the code without parts replacement.
The code can set intermittently due to a vacuum leak that only appears under certain temperature or load conditions, making visual inspection of all vacuum lines essential.
Some vehicles use the bypass valve for both boost control and emissions reduction, so a fault may also trigger secondary codes or drivability issues unrelated to performance.
A faulty bypass valve can mimic a failing turbocharger, leading to unnecessary replacement of expensive components if the valve is not tested first.
After repairs, the code may require a drive cycle or a relearn procedure to clear, and simply erasing the code may not be sufficient for the monitor to run.

Can I keep driving with P2C29?

You can usually drive the vehicle with this code, but avoid aggressive acceleration or heavy load because the bypass valve may not regulate boost properly, which can lead to reduced power or potential engine damage over time. Have the fault diagnosed soon to prevent worsening performance or secondary issues.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.