What it means
The redundant park pawl position sensor B reads below the lower diagnostic threshold. Redundancy for the park-engagement check is lost.
At a glance
- Usually lights the check-engine light
How it works
Park pawl position sensor B is the redundant signal used to confirm whether the transmission's mechanical pawl is engaged in Park. The shift-by-wire controller checks this second sensor's signal alongside the primary confirmation. P271C sets when sensor B's signal falls below the diagnostic threshold, so the controller may lose the redundant confirmation even if sensor A appears normal.
Common causes
Most likely first.
- Internal short in sensor element
- Signal wire shorted to ground
- 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 B status with sensor A, the selected gear, and the Park indication.
- Inspect sensor B's connector and wiring for corrosion, damaged pins, fluid, or a signal wire shorted to ground.
- Check the sensor B signal and reference circuit using the manufacturer's wiring diagram and test procedure.
- Test sensor B for an internal short and compare its readings with the manufacturer's specification.
- If sensor B and its circuit pass, investigate the shift-by-wire controller and the pawl-position mechanism.
Common fixes
- Repair a sensor B signal wire shorted to ground.
- Clean or repair corroded connector pins at sensor B.
- Replace sensor B if testing confirms an internal short.
- Repair the pawl-position mechanism or controller only if tests identify a fault there.
Can I keep driving?
Use the parking brake whenever the vehicle is parked and do not assume Park is securely confirmed if the gear warning is present. If shifting or starting is restricted, avoid driving 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.