Powertrain, generic (extended)

P277F Clutch B Unexpected Mechanical Gear Disengagement

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

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

Symptoms

  • Momentary loss of drive in an even gear
  • Even gears unavailable, gearbox skips between odd gears
  • Warning lamp with stored transmission fault

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–3,500
Time1–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

dual clutch bhydraulic actuator

Related codes

P277EP2711P284D

References: gsi.ext.gm.com, fordservicecontent.com, law.cornell.edu.