P2C29 code meaning
Turbocharger/Supercharger Bypass Valve B Stuck
Powertrain system Generic code P2Cxx codes Check engine light
What P2C29 means
Bypass valve B is the compressor recirculation valve of the second charger – the later one in series layouts, the bank 2 unit on parallel twin-turbo engines. It is not the wastegate. P2C29 means a position-controlled valve no longer follows its target and stays where it is. No manufacturer documents P2C29 publicly. The A-side twin P23AA shows the method on GM's 2019 Corvette LT5: a position error above 25 % lasting at least 1 s while the valve barely moves (under 10 %/s), 10 of 14 samples, Type A. GM's 2019 CT6 4.2L twin-turbo, by contrast, uses switched dump valves without a sensor for both banks and reports a sticking valve B as P00C4. Stuck closed causes surge noise on lift-off; stuck open costs boost.
P2C29 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2C29
- Check engine light
- Less boost and power
- Fluttering compressor noise when lifting off
Common causes of P2C29
- Most likelyOil or carbon deposits binding the valve flap or piston
- PossibleWorn gears or motor in the electric actuator
- Less likelyBent shaft or damaged housing of the valve
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Turbo bypass valve bWiring harnessECM
What each part of P2C29 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 29 | The exact fault in that area. |
What to do next
- Note P2C29 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2C29
What does P2C29 mean?
P2C29 means "Turbocharger/Supercharger Bypass Valve B Stuck". Bypass valve B is the compressor recirculation valve of the second charger – the later one in series layouts, the bank 2 unit on parallel twin-turbo engines. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C29?
Drive gently and only to a workshop. With P2C29 the car can go into limp mode (reduced power) to protect itself.
Will P2C29 fail an emissions test?
Yes, it can. P2C29 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2C29 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P2C29 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.