P277FClutch B Unexpected Mechanical Gear Disengagement
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P277F is the even-gear twin of P277E: the controller has found that a gear carried by the shaft of clutch B lost its engagement on its own while the car was driving through that clutch. The evidence comes from speed sensors, which show the synchronizer of the active gear turning at a different speed even though clutch B is practically locked (GM: slip below 50 rpm, 1 s confirmation, Type A in the 2023 dual-clutch TCM tables). Ford's 2024 summary assigns the code to the even clutch shaft of its TR9070 gearbox. Typical reasons are worn fork detents or engagement teeth, a shift rod that creeps because of hydraulic leakage, or a fork position learned wrongly after a repair. The even gears are then often locked out, and a relearn with a scan tool is normally part of the fix.
- What you may notice
- Momentary loss of drive in an even gear
- Even gears unavailable, gearbox skips between odd gears
- Warning lamp with stored transmission fault
- Likely causes
- LikelyWorn detent or engagement teeth on an even gear or its sleeve
- PossibleShift rod of the even shaft creeping due to leakage in the hydraulic unit
- PossibleWrong or missing fork position learning after repair
- RareImplausible even-shaft speed signal
- 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 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.