Why does the car still roll when in P gear?
2 Answers
The reason the car still rolls when in P gear is that the vehicle is parked on a slope, which can cause rolling. P gear is a common gear position in automatic transmission vehicles, usually located at the foremost position on the gear shift console, in front of the R gear, designed to lock the axle when the car is stationary on a slope. After shifting into P gear, the handbrake should be firmly engaged; otherwise, it may cause excessive force on the P gear locking mechanism, reducing its service life. The correct method is to shift into N gear first, engage the handbrake, and then shift into P gear. This approach can extend the service life of both the transmission and the P gear locking mechanism.
I had the same issue before. The car actually rolled on a slope after parking in P gear, which was really scary. Later, I asked a professional technician and learned that the P gear locking mechanism mainly relies on a pawl in the transmission hooking onto the gear to achieve braking. However, if parked on a steep slope or subjected to excessive force, this small metal hook might be forcibly pushed open. Additionally, when the transmission fluid temperature is too high, parts expand, which can also reduce the locking effect. Another possibility is parking too quickly—shifting into P gear before the car comes to a complete stop, causing the inertia of the wheels turning the gear to bounce the pawl open. During repairs, I found that my car's transmission fluid had aged and wasn't replaced in time, leading to insufficient lubrication and reduced friction resistance between metal parts. Now, I’ve developed a habit when parking: first press the foot brake, wait for the car to come to a complete stop before shifting into P gear, and finally pull the handbrake tight. This triple safety measure gives me much more peace of mind.
