P278F code meaning
Clutch B Adaptive Learning at Limit
Powertrain system Generic code P27xx codes Check engine light
What P278F means
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.
P278F at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 8 hours
- Clears after repairAfter a drive cycle
Symptoms of P278F
- Shudder or slip when an even gear takes over
- Rough or slow shifts between gears
- Transmission warning lamp
Common causes of P278F
- Most 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
- Less likelyOutdated software or inaccurate engine torque information
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Dual clutch bTCM
What each part of P278F means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 8F | The exact fault in that area. |
What to do next
- Note P278F and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P278F
What does P278F mean?
P278F means "Clutch B Adaptive Learning at Limit". P278F flags that the learned values for clutch B have run out of room. It is a generic code, so it means the same on every make.
Is it safe to drive with P278F?
Drive gently and only to a workshop. With P278F the car can go into limp mode (reduced power) to protect itself.
Will P278F fail an emissions test?
P278F is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P278F to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 8 hours of work. This is a job for a workshop.
Will P278F clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.