What it means
The signals from park position sensors or switches A and B do not agree as expected.
At a glance
- Usually lights the check-engine light
How it works
The transmission control module compares park-position sensor or switch A with sensor or switch B to confirm selector position. This code sets when their reported positions disagree beyond the expected correlation, which can happen if one signal drifts or the shift mechanism is misadjusted.
Common causes
Most likely first.
- One of the two sensors drifting outside tolerance
- Mis-adjusted shift lever mechanism
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
How to diagnose it
- Read freeze-frame and live transmission data to see which selector position was reported by A and B when their readings disagreed.
- With the vehicle safely parked, move the selector through each position and compare the A and B readings for agreement.
- Inspect both sensor or switch connectors and wiring, since a fault in either signal can create a false disagreement.
- Check the shift linkage or lever mechanism for looseness, wear, or misadjustment that could prevent both sensors from tracking the same position.
- Test both sensor outputs and the module inputs against the manufacturer's specification to identify which side is out of range.
Common fixes
- Secure or clean a loose or corroded connector at sensor A or B.
- Repair damaged wiring in the affected sensor circuit.
- Adjust the shift linkage or sensor alignment where the vehicle design allows it.
- Replace the sensor or switch shown by testing to be drifting.
- Repair the transmission control module input circuit if both sensor signals and linkage check correctly.
Can I keep driving?
Avoid driving if the vehicle does not reliably recognize the selected gear or shifts unpredictably; arrange a tow if it cannot be controlled safely. A continuing mismatch can trigger limited operation and may worsen transmission problems.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.