Is Idling Harmful to Cars?

[OBrantley]

Idling is harmful to cars, and the hazards include: 1. Increased engine carbon deposits; 2. Shortened engine lifespan; 3. Overly rich air-fuel mixture in the engine, which can easily damage the three-way catalytic converter; 4. Loosening of the vehicle's braking system, increasing the risk of accidents; 5. Increased exhaust emissions from the vehicle's cylinders. Car idling refers to an operating condition where the engine runs without load, only overcoming internal friction resistance without outputting power, maintaining the minimum stable engine speed. The idle speed can be adjusted by modifying the throttle opening and idle fuel supply.

[JeffreyFitz]

Having driven for nearly twenty years, my experience is that prolonged idling is definitely harmful. I used to think it was necessary to warm up the car for half an hour in winter, but later learned it's unnecessary. At idle, the engine runs at low RPM, leading to incomplete combustion of gasoline, which causes carbon buildup in the cylinders. Over time, the car starts to shake and loses acceleration power. A friend of mine always idled with the AC on while waiting, and during repairs, we found the spark plugs completely blackened—replacing them didn’t help as they fouled again quickly. Idling also consumes a lot of fuel, burning over a liter per hour, essentially wasting money. Not to mention, the oil pump pressure is insufficient during idling, which can shorten the engine's lifespan over time. Now, I either turn off the engine and step out or limit idling to just a few minutes before driving off slowly.

[WestonLynn]

I think idling is the most harmful to both the wallet and the environment. Parking without turning off the engine means the engine is running idle, still burning fuel and emitting exhaust for nothing. Tests have shown that idling for an hour consumes more fuel than driving ten kilometers, wasting money and causing pollution. Many cities now impose fines for idling for more than three minutes, and for good reason. Although newer car technologies have reduced emissions during idling, it's still best to avoid it whenever possible. Moreover, prolonged idling can lead to severe carbon buildup in the car, increasing maintenance costs in the long run. I usually turn off the engine if I'm stopping for more than a minute. If I really need to keep the air conditioning on while waiting, I find a shady spot and open the windows for ventilation—saving fuel and being eco-friendly.

[CharlieDella]

When buying my first car, I often heard people say that idling damages the engine. Later, after researching, I understood the reason. During idling, the engine temperature doesn't rise sufficiently, gasoline doesn't burn completely, and carbon deposits can stick to the spark plugs and throttle body. Once in winter, I idled for half an hour waiting for someone, and later when accelerating, the car jerked. Upon inspection, I found the fuel injectors were clogged. Nowadays, many car manuals explicitly state to avoid prolonged idling. For short warm-ups, three minutes is enough, and driving slowly for a kilometer after starting is even more effective. So unless it's dozens of degrees below zero, I usually start driving slowly after just thirty seconds.

[MatteoDella]

Auto repair shops often deal with issues caused by idling. A common problem is carbon buildup clogging the oxygen sensor, causing the check engine light to come on randomly. In severe cases, the entire sensor set may need replacement. Especially for cars idling with the AC on, the alternator can't keep up with the power demand, doubling the battery's aging rate. One customer had to replace their battery after just two years due to prolonged idling with the AC on. It's recommended to avoid continuous idling for over ten minutes, regularly drive on highways to clean carbon deposits, or add some fuel additives to maintain the fuel injectors.