What it means
The position sensor for park pawl A reads above the upper diagnostic threshold. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Park pawl position sensor A signals whether the transmission pawl has engaged Park. The shift-by-wire controller monitors that signal to verify the pawl state before permitting related shift or start functions. P271B sets when sensor A's signal rises above its diagnostic threshold, which can indicate an open sensor or a signal wire shorted to the 5 V reference.
Common causes
Most likely first.
- Open sensor element
- Signal wire shorted to the 5 V reference
- Connector pins corroded - high contact resistance
Symptoms
- Transmission or gear-selection warning light may be on
- Park engagement may not be recognized reliably
- Vehicle may be restricted from shifting or starting
How to diagnose it
- Save freeze-frame data and compare live sensor A status with the selected gear and the vehicle's Park indication.
- Inspect sensor A's connector seals, pins, and harness for water entry, pin push-back, chafing, or an open connection.
- Check whether sensor A's signal is high with the connector connected and during a careful harness movement check, following the manufacturer's procedure.
- Test the signal wire for a short to the 5 V reference and check sensor continuity against the manufacturer's specification.
- If the signal circuit and sensor pass, investigate the shift-by-wire controller and pawl-position mechanism.
Common fixes
- Repair chafed wiring that shorts sensor A's signal to the 5 V reference.
- Restore a pushed-back or corroded connector pin and reseal the connector if needed.
- Replace sensor A if its element is open.
- Repair the pawl-position mechanism or controller if testing confirms that is the source.
Can I keep driving?
If Park is not reliably confirmed, apply the parking brake and do not leave the vehicle on a slope; it may also be restricted from shifting or starting. Avoid driving if gear selection is unreliable and arrange service.
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.