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.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- Momentary loss of drive in an even gear
- Even gears unavailable, gearbox skips between odd gears
- Warning lamp with stored transmission fault
Most likely causes
- Worn detent or engagement teeth on an even gear or its sleeve
- Shift rod of the even shaft creeping due to leakage in the hydraulic unit
- Wrong or missing fork position learning after repair
- Implausible even-shaft speed signal
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P277F means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 7: Transmission
- 7F: Specific fault in that system
Frequently asked questions
Can I keep driving with code P277F?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P277F?
The most common causes are: worn detent or engagement teeth on an even gear or its sleeve; shift rod of the even shaft creeping due to leakage in the hydraulic unit; wrong or missing fork position learning after repair.
Related codes
- P277EClutch A Unexpected Mechanical Gear Disengagement
- P2711Unexpected Mechanical Gear Disengagement
- P284DShift Fork A Unrequested Movement
Sources
- gsi.ext.gm.com: 23OBDG07
- fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001
- law.cornell.edu: 13 CCR 1968.2
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.