P2878Clutch B Disengagement Time Too Fast
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2878 reports that clutch B lets go sooner or more abruptly than the release ramp held in the control unit. During a powershift the outgoing clutch has to keep carrying torque until the incoming one has taken over; if clutch B drops out early, the engine flares for a moment and the next gear arrives with a jolt, mostly on shifts away from reverse and the even gears. No manufacturer publishes detection criteria for P2878; CARB 13 CCR 1968.2 is the legal basis. Ford's DPS6 summary shows why timing errors arise on dry designs: a motor turns a screw-driven fulcrum, hall sensors count its travel from an end stop, and a spring pulls the clutch open as soon as the motor lets go. A lost position count, a weak hold or adaptation values that no longer match the linings all shorten the release.
- What you may notice
- Brief engine flare followed by a jolt when shifting
- Harsh shifts out of even gears or reverse
- Warning lamp, firmer substitute shift program
- Likely causes
- LikelyClutch B adaptation values no longer matching the linings
- PossibleActuator position count lost or misread by the hall sensors
- PossibleOn wet systems a clutch B valve venting pressure too quickly
- RareLow fluid level or aerated fluid
- 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: €80 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.