P284B
Shift Fork C Stuck
Shift fork C cannot leave its current engagement position when the actuator commands movement. Mechanical jam or actuator without travel.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Ordered by how often each turns out to be the cause.
- Shift fork mechanically jammedCommon
- Synchroniser teeth damagedPossible
Parts involved
- Shift Fork C
- Shift Fork Actuator C
- Synchroniser Assembly
P284B is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.