P277F code meaning
Clutch B Unexpected Mechanical Gear Disengagement
Powertrain system Generic code P27xx codes Check engine light
What P277F means
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.
P277F at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P277F
- Momentary loss of drive in an even gear
- Even gears unavailable, gearbox skips between odd gears
- Warning lamp with stored transmission fault
Common causes of P277F
- Most 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
- Less likelyImplausible even-shaft speed signal
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Dual clutch bHydraulic actuator
What each part of P277F 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. |
| 7F | The exact fault in that area. |
What to do next
- Note P277F 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 P277F
What does P277F mean?
P277F means "Clutch B Unexpected Mechanical Gear Disengagement". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P277F?
Drive gently and only to a workshop. With P277F the car can go into limp mode (reduced power) to protect itself.
Will P277F fail an emissions test?
Yes, it can. P277F is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P277F to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will P277F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.