P2CD5Turbocharger/Supercharger Bypass Valve C Stuck
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Bypass valve C is a third compressor recirculation valve, which only exists on layouts with three charging paths or stages; on lift-off it routes boosted air back to the compressor inlet so the compressor does not surge. It is not the wastegate. P2CD5 says the valve no longer moves when commanded and stays in one position. No manufacturer documents P2CD5 publicly. GM shows the two usual methods on its A and B valves: the 2019 Corvette LT5 flags P23AA when the position error exceeds 25 % for 1 s while the valve speed stays within ±10 %/s (Type A), and the 2019 CT6 twin-turbo infers a stuck dump valve on bank 2 from airflow and pressure behaviour (P00C4). A circuit fault on valve C is P25F8, a general mechanical fault P25FC. Stuck shut means surge noise on lift-off, stuck open means missing boost.
- What you may notice
- Fluttering or surging noise from the intake when lifting off the throttle
- Boost builds slowly or stays low when the valve is stuck open
- Warning lamp on and engine power limited
- Likely causes
- LikelyValve or piston seized by oil and soot deposits from the crankcase breather
- PossibleElectric actuator or diaphragm of the valve worn or failed
- PossibleMissing vacuum or control signal on a pneumatically operated valve
- RarePosition feedback reports movement wrongly although the valve works
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.