Why Does the Car Still Roll When in P Park?

[KatherineMarie]

If you directly shift into P Park and stop the car on a slope, the vehicle may roll. For safety reasons, always engage the parking brake when parking. Below is relevant information about the parking brake: 1. Principle: The professional term for the parking brake is auxiliary brake. Unlike the main braking system, the parking brake uses a steel cable connected to the rear brake shoes to stop the car. Prolonged use of the parking brake can cause the steel cable to undergo plastic deformation. Since this deformation is irreversible, long-term use will reduce its effectiveness and increase the parking brake's travel distance. 2. Supporting Tool: A return spring is used in conjunction with the parking brake. When the parking brake is engaged, the spring stretches; when released, the spring returns to its original length. With prolonged use, the spring will also undergo corresponding deformation.

[McEmery]

I often drive automatic transmission cars, and this issue is indeed alarming. If the car still rolls after shifting to P (Park), it's most likely because the parking pawl isn't fully engaged. This could happen if the car wasn't completely stopped or if the ground is on a slope. On an inclined surface, the vehicle's weight can't be held by the P gear alone—the transmission's pawl might not have locked properly, or there could be debris obstructing it. Next time you park, especially on a slope, make sure to firmly press the brake, shift to P, engage the parking brake, and then release the foot brake to ensure safety. Sometimes, aged transmission fluid or worn internal components can also reduce locking strength, so regular transmission maintenance is crucial. If this happens with a new car, take it to the dealership for inspection immediately—don't ignore it. I once experienced this on a steep hill and was fortunate to engage the electronic parking brake in time.

[StAlexis]

Our family has been driving for many years, and this often happens when parking on a slope. After shifting to P gear, the car still rolls forward or backward, mainly because the parking mechanism isn't secured properly, and the weight on a steep slope prevents it from locking firmly. Another possibility is an internal transmission issue, such as gear wear or an obstruction. When parking, it's always recommended to shift to N gear first on a slope, engage the handbrake firmly, then shift to P gear, and release the foot brake slowly. Pay attention to the parking environment and avoid parking on steep slopes. Additionally, if the vehicle is used for a long time without maintenance, dirty transmission fluid can weaken the locking force, so it's best to check it every few tens of thousands of kilometers. Although this problem doesn't occur frequently, it can be quite dangerous when it does, so handle it with care.

[MacColton]

I've encountered this situation before. The root cause of the car rolling in P gear is a failure in the parking system. The transmission's ratchet and pawl mechanism may not be properly engaged, possibly due to incorrect wheel positioning when parking or a system malfunction. A simple check method is to firmly press the brake next time you park, engage the handbrake first, then shift to P gear, and observe if the car still rolls. If this issue persists, professional diagnosis is needed as there may be damage to transmission components. Parking habits are also crucial - ensure the ground is level. Ignoring this problem may lead to long-term damage to the transmission.