Two problems related to transmission not go into gear have been reported for the 2008 Toyota Prius. The most recently reported issues are listed below.
Vehicle will not stay in gear, usually hot days when it happen. Weather its in rev or drive it will shift back to neutral. It started July 2011. Took it to dealer they could not duplicate. Now yesterday may 27th it happen again. You would have to hold down or up gear shift to have gear stay in place.
The contact owns a 2008 Toyota Prius. The contact stated that the gear shift interlock had to be depressed in order to unlock and shift the vehicle into any gear. If the button was not depressed, the vehicle would not recognize he gear and place the vehicle in neutral. The contact stated that in order to drive forward or in reverse, the button had to be abnormally held down while driving until the vehicle was shut off. If the button was not depressed, the vehicle would shift into neutral independently. The vehicle was not inspected or repaired for the failure. The failure and current mileage was 94,000.