Powertrain
Definition only
Lights the check engine lamp
P284B: Shift Fork C Stuck
Standardized SAE J2012 code · P28xx codes
What does P284B mean?
Shift fork C cannot leave its current engagement position when the actuator commands movement. Mechanical jam or actuator without travel.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
- High Shift fork mechanically jammed
- Medium Synchroniser teeth damaged
Likelihood is a general estimate across vehicles; your make and model may differ.
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