Powertrain
Definition only
Lights the check engine lamp
P2851: Shift Fork Position Sensor A/B Correlation
Standardized SAE J2012 code · P28xx codes
What does P2851 mean?
The position signals of shift fork sensors A and B do not correlate as expected for the active gear pre-selection. Plausibility check fails.
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 Offset between the two sensors after replacement
- Medium Sensor harness incorrectly swapped
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2851 on the same make and model first.
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