P284FShift Fork C Unrequested Movement
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P284F covers drift of fork C away from its held gear. In GM's Corvette software this is rod 3, which sits on the shaft of the even clutch; the check compares the rod position with the learned point for the gear that the even clutch speed and the output speed confirm, and sets a Type A code once the wide limit is exceeded long enough or the drift correction keeps firing. The repair routine that follows works on the even shaft. Ford is inconsistent: its 2024 TR9070 table for the four rod sensors lists rod 3 drift as P277E, whereas a second table in the same summary, sorted by shift rod, gives P284F. Mechanical causes are the same as for the other forks, though only the gears of fork C are withdrawn while the fault is active.
- What you may notice
- Even-shaft gear disengages unexpectedly
- Shift flare or jerk while cruising
- Warning lamp with stored code
- Likely causes
- LikelyResidual pressure on the fork C actuator from a leaking valve
- PossibleRod 3 sensor reading offset so the fork appears to move
- RareWorn detent or synchronizer parts at fork C
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · 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.