OBD Codes List

Diagnostic reference · P284F

P284F

Shift Fork C Unrequested Movement

System
Transmission (P code)
Lamp
Check Engine Light
Category
Powertrain - Transmission

What it means

P284F means Shift Fork C Unrequested Movement.

Check these first

  • A shift fork C that moves without a command
  • A leaking shift fork C actuator seal
  • A failed shift fork C position sensor
  • Debris holding the shift fork C valve open

What to do next

  1. Read shift fork C position on a scan tool at rest
  2. Watch for shift fork C movement with no shift commanded
  3. Command shifts and confirm the shift fork C moves only on command
  4. Test the shift fork C actuator for a leaking seal
  5. Replace the shift fork C actuator if it moves uncommanded
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.