Powertrain
Definition only
Lights the check engine lamp
P284F: Shift Fork C Unrequested Movement
Standardized SAE J2012 code · P28xx codes
What does P284F mean?
Shift fork C moves without an actuator command. Hydraulic leakage at the actuator or detent spring failure.
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 Internal leak in fork actuator
- Medium Detent spring or ball failed
Likelihood is a general estimate across vehicles; your make and model may differ.
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