P278FClutch B Adaptive Learning at Limit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P278F flags that the learned values for clutch B have run out of room. In a dual-clutch gearbox this is usually the clutch for the even gears; the controller keeps adjusting its touch point and pressure or travel so that handovers between the two clutches stay seamless, and stores the code once a correction hits its end stop. No manufacturer documents P278F publicly with set conditions; CARB requires such transmission functions to be monitored. What the clutch A sibling P2789 shows in Allison's bulletins applies here too: software and an implausible engine torque signal are checked first, worn or damaged plates second. On dry clutches, wear increases the release travel until the learned range is used up. Expect shudder on even gears, slow or rough handovers and a warning lamp; P2788 is the system-level code.
- What you may notice
- Shudder or slip when an even gear takes over
- Rough or slow shifts between gears
- Transmission warning lamp
- Likely causes
- LikelyWorn clutch B lining or plates shifting the touch point
- PossibleClutch adaptation not reset or relearned after repair
- PossibleClutch B actuator or release mechanism sticking or losing pressure
- RareOutdated software or inaccurate engine torque information
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.