Transmission Self Shifts from Park to Reverse

National Highway Transportation Safety (NHTSA) refers to the "Park-to-Reverse" issue as  "Unintended Powered Roll-Away" and has opened numerous investigations of these events over the last 35 years.




NHTSA refers to the "Park-to-Reverse" issue as  "Unintended Powered Roll-Away" and has opened numerous investigations of these events over the last 35 years

Instead of immediately defaulting into gated park or reverse as a properly designed transmission should, the vehicle’s transmission can be shifted to between gears where it can self engage powered reverse after a dwell or delay period of a few seconds to several minutes or longer

History of automobile development and the mechanical cause of the defect


Park to Reverse” issues are nearly always caused by a design flaw 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 appears 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.


From this False Park position, slight movements in the vehicle, vibration, or the build up of hydraulic pressure in the transmission can then cause the vehicle to reengage powered reverse after a delay from a few seconds to longer periods of time (what is called a "self shift"). This will cause the vehicle to suddenly and without warning move backwards unexpectedly under engine power.

If the driver has exited the vehicle with the engine running (to for example, retrieve an item, open a gate, or close a garage door, etc.), a vehicle in false park can shift into powered reverse from a few seconds to several minutes, after the driver has exited, and then run over the driver or a bystander.



False Park is a term to describe when a vehicle is between the Park and Reverse gear positions, without the parking pawl engaged.


Slight movements in the vehicle, vibration, or the build up of hydraulic pressure in the transmission can then cause the vehicle to reengage powered reverse

Show More

Mechanical causes of the "inadvertent movement", "Park-to-Reverse", or "False Park" problem

Manufacturers and models susceptible to inadvertent movement

Park-to-Reverse injury and death cases

The park-to-reverse defect may be described using different terms depending upon the factual situation of an accident or event.   All involve a driver who believes that he/she has 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 is then a delay in vehicle movement sufficient for the driver to either fully or partially exit the vehicle before vehicle movement starts.   Typically, the vehicle will move backwards in powered reverse.  However, when placed in "false park" (the vehicle is between the park and reverse gear position; i.e. "false park" and the transmission is in hydraulic neutral, without the parking pawl engaged),  the vehicle can also roll either forward or back in neutral without shifting into a powered gear.   While less common, transmissions with the defect, can also be shifted to between neutral and drive, and then self shift into drive (called a "neutral to drive" accident).

Scott P. Nealey is a San Francisco-based plaintiff's side trial attorney.  He is the founder and principal of Nealey Law, a San Francisco based trial-focused, plaintiff law firm litigating complex class action, consumer and product liability nationwide.  Scott Nealey was the lead counsel in Mraz vs. DaimlerChrysler (2007) and in Guillot vs. Chrysler (2008)  both of which were park-to-reverse cases tried to verdict (since the Jimmy Carter era).  For his work in Mraz, Scott received the 2007 California Lawyer Attorney of the Year (CLAY) Award and was named a Finalist for San Francisco Trial Lawyer of the Year in 2008.  Scott was also named one of the Northern California Super Lawyers and San Francisco's Best Lawyers 2012 and 2016.

The material on this website is intended for public education and informational purposes only and does not constitute legal advice. The material is not guaranteed to be complete, or up to date.

This information is not intended to substitute for obtaining legal advice from an attorney.

  • facebook-square
  • google-plus-square
  • LinkedIn Basic Black

© 2018 by Nealey Law  | All Rights Reserved