P08C4Pressure Control Solenoid M Performance/Stuck Off
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- GM sets this code on the Corvette's Tremec dual clutch when synchronizer actuation valve 1, the valve for the odd-gear shaft, is hydraulically stuck off. The test runs inside a synchronizer recovery or integrity routine, started after a shift-related fault or when the stored gear does not match the sensed gears at start-up: the shift rods are moved slightly, and if a rod travels 100 µm or less where the valve should move it, a current profile check of the valve has to fail three times before the fault is confirmed. Type A, MIL at once. Bulletin 21-NA-033 blames debris; the fix is GDS valve cleaning three times, service clean and fast learn, and a new control valve body only if it returns.
- What you may notice
- Check engine light on
- Odd gears not engaged or engaged late
- Noise from the transmission area
- Likely causes
- LikelyValve stuck closed by debris in the control valve body
- PossibleDebris from a dislodged snap ring in the direct clutch assembly (bulletin 23-NA-197)
- RareLow system pressure or fluid level
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.