What is "park-to-reverse"

A park-to-reverse defect is a term used to describe several scenarios in which cars with automatic transmission can fail to properly engage the parking mechanism, causing the vehicle to unintentionally roll, sometimes resulting in injury or vehicular accidents. The term has significance in product liability law, and in a number of major cases in the United States have been brought in which car manufacturers were accused of negligence for not addressing an alleged dangerous flaw in the transmission.

A "park-to-reverse" situation involves a driver who believes that they have shifted into "park" and believing so, and the vehicle not moving when they pull their foot off the brake, proceeds to exit the vehicle. There can then be a delay in vehicle movement sufficient for the driver to either fully or partially exit the vehicle before the vehicle moves. Typically, the vehicle will move backwards. However, when on certain vehicles the shift selector can be placed between the detented park and reverse gear positions; i.e. in "false park" the transmission is in hydraulic neutral, without the parking pawl engaged. As such the vehicle can also roll either forward or back in neutral. While less common, transmissions with the defect, can also be shifted to between "neutral" and "drive", and then self shift into "drive" or roll (called a "neutral to drive" accident).

"Park-to-Reverse" issues are nearly always caused by several possible design flaws in a vehicle's transmission which makes it possible for a driver to unknowingly place the vehicle's shift selector into a position in between the "park" and "reverse" gear positions. Yet rather than being in "park', this area is a transitional zone between gears, which is sometimes called "false park".

When a vehicle's transmission is in false park, it may appear to the driver that the vehicle is fully locked in park. However, on vehicles with this defect the transmission is neither in park nor in hydraulic reverse. Instead, it is in neutral, an unstable position between the two gears.