P2C9BCold Start Turbocharger/Supercharger Wastegate Actuator A Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2C9B checks wastegate A while the engine runs its catalyst warm-up strategy after a cold start, when the wastegate is commanded open so hot exhaust reaches the catalyst rather than the turbine. GM uses the code on the 2.7-litre L3B (table 19OBDG03D): it fails if the position error stays above 20 % for over 1 s, the actuator current above 1 A or the duty cycle above 40 %, judged on 25 of 30 samples at 100 ms; Type A, MIL after one trip. The 2025 table 25OBDG03B tightens the position limit to 10 % over 2 s (29 of 30). In the 19OBDG07 table for GM's twin-turbo 4.2-litre V8 the code flags a bank 1 bypass valve that sticks longer than 1 s during rapid heat-up. Causes are a stiff flap or linkage, a weak electric actuator or wiring. P2B81 covers the actuator outside cold start; P2C9C is turbo B.
- What you may notice
- Check engine light shortly after a cold start
- Rattle or noise from the wastegate area when cold
- Often no noticeable change in performance
- Likely causes
- LikelyWastegate flap or linkage stiff from corrosion or deposits, worst when cold
- PossibleElectric wastegate actuator with worn motor or gears
- RareActuator position feedback incorrect
- RarePoor contact at the actuator connector or wiring
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.