Powertrain, generic (extended)

P284A Shift Fork B Stuck

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P284A is stored when fork B stays put although the transmission module commanded a move, for instance from neutral toward an engaged gear or back. Published strategies avoid this code. Ford's 2024 summary for the TR9070 dual-clutch box diagnoses the same symptom per gear rather than per fork, with failure-to-engage codes such as P073F and failure-to-disengage codes such as P072B, while GM's Corvette software folds a motionless rod into its position-sensor consistency checks. The CARB 13 CCR 1968.2 functional check of transmission components covers the case either way. For the driver, the gears carried by fork B disappear; if the fork hangs in an engaged gear, the module may have to drive around it on the other shaft. Inspection usually means opening the gearbox.

Likely causes

Fork B actuator, solenoid or hydraulic supply failing to apply force
Synchronizer of fork B gears jammed or damaged
Contaminated fluid restricting the fork B actuator

Symptoms

  • Gears of fork B missing or a gear stays engaged
  • Warning lamp and emergency mode
  • Rough starts or lack of drive in some gears

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–4,500
Time2–12 h

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

Parts involved

shift fork bshift fork actuator bsynchroniser assembly

Related codes

P2849P284BP284CP073FP072B

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