P2856Clutch B Pressure Charge Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2856 flags too much pressure at clutch B, the even-gear clutch in GM's and Ford's dual-clutch layouts. For the Corvette unit GM checks clutch 2 with the same high-side logic as clutch 1, including the hold-pressure case: an open clutch held at its standby pressure must not rise well above that point, because it would then pass torque while the other clutch is driving. A Type A code follows, and the even clutch recovery routine is requested. Ford's 2024 summary lists P2856 on the TR9070 for even clutch pressure above target. Both clutches carrying torque at once can make the car shudder or brake itself, so continuing on the odd gears with clutch B open is the likely fallback.
- What you may notice
- Shudder or binding during shifts
- Even gears blocked, emergency program
- Warning lamp
- Likely causes
- LikelyClutch B pressure control valve hanging in a high-pressure position
- PossibleSafety shutdown valve for clutch B not venting
- RareClutch B pressure sensor reading high within its range
- 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: €200 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.