P271D: Park Pawl Position Sensor B Circuit High
What to do
Always apply the parking brake when you park, and do not rely on P alone. The car may not be able to confirm the park lock has engaged. On a hill, turn the front wheels into the kerb as well. Get it diagnosed promptly — a rollaway is exactly what this system exists to prevent.
What this code means
Park pawl position sensor B is reading high.
The park pawl is the only thing physically stopping a parked car from rolling away, and shift-by-wire made it an electrical component.
It is a steel tooth that drops into a toothed wheel on the output shaft. On a car with a mechanical linkage, moving the lever to P pushes it there through a cable and the driver feels it engage. On shift-by-wire there is no linkage — the lever is a switch, and a motor moves the pawl. Which means the car has to know the pawl engaged, and has to tell the driver when it did not.
That is why these codes matter more than their part cost suggests. A pawl that has not engaged leaves the car held only by the parking brake, and on a slope by nothing at all if the brake is also electric and has not applied.
Sensors A and B are a redundant pair, and the redundancy is the design rather than a luxury: the car must be able to tell "the pawl is out" from "the sensor that reports the pawl is broken", and one sensor cannot distinguish those. Two disagreeing is a detectable fault; one silently wrong is not.
A high reading is usually an open circuit or a short to voltage. The sensor sits on the transmission in road spray and heat, so the connector and the harness fail more often than the sensor.
Until it is fixed, use the parking brake every time and treat P as unconfirmed. On a slope, turn the wheels into the kerb. That advice is not excessive — a rollaway is the failure mode this system exists to prevent.
Likely causes
Start here
- Corroded or loose connector · specialist
- Faulty park pawl position sensor · specialist
- Damaged wiring harness · specialist
Less common
- Open circuit in solenoid wiring · specialist
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
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Community experience
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