Does leaving the car in P gear without turning off the engine for a long time damage the vehicle?
3 Answers
Leaving the car in P gear without turning off the engine for a long time can damage the vehicle. The P gear locks the transmission gears, which can cause impact on the transmission. The effects of leaving the car in P gear without turning off the engine for a long time include: 1. The intake vortex weakens, leading to poor fuel atomization and incomplete fuel combustion; 2. Increased fuel consumption by the engine; 3. Deterioration of lubrication conditions. The gears on an automatic transmission car are divided into: P for Park, R for Reverse, N for Neutral, D for Drive, L for Low, and S for Sport mode. When the vehicle needs to be parked for a long time, especially on a slope, it should be shifted to P gear, at which point the wheels are mechanically locked, ensuring the vehicle cannot move while stationary.
The other day at the repair shop, I was chatting with the mechanic about the issue of leaving the car in P gear without turning off the engine. The mechanic said the transmission isn't really a concern—P gear is specifically designed for parking, and the locking mechanism can hold the car steady. But keeping the engine running at low RPM isn't ideal; burning fuel like that isn't exactly economical. Over time, carbon buildup becomes a problem, especially with direct-injection engines—if the fuel injectors get clogged, repairs can cost hundreds. In summer, it's even more critical. Running the AC compressor continuously while idling can lead to overheating. The most extreme case I've seen was someone idling for three hours and draining the battery, eventually needing a rescue vehicle. If you're waiting for more than twenty minutes, it's much better to turn off the engine, get out, and stretch your legs.
I remember last winter when I used to idle the car to keep warm while waiting to pick up my child from tutoring classes, which caused my fuel consumption to skyrocket. Later, I did some research and found out that when idling in P gear, the transmission gears are completely disengaged, resulting in minimal mechanical loss. The real issue lies with the engine's operating condition: the combustion chamber doesn't reach the optimal temperature, leading to incomplete fuel combustion, and the throttle body can accumulate black carbon deposits in just two weeks. Last year, I spent over 500 yuan just to clean the carbon buildup in my car. Now I've learned my lesson—if I have to wait for more than ten minutes, I turn off the engine, which saves fuel and is better for the environment. If you're worried about staying warm in winter, bringing a thermos is much more cost-effective than running the heater, and it can also extend the lifespan of your car battery by a couple of years.