What are the causes of engine stalling at idle?

[VanLily]

Car engine stalling at idle can be caused by: 1. Damage to the engine idle control valve or its wiring; leakage in the vacuum pipe of the brake vacuum booster; damage to the diaphragm of the brake vacuum booster; air leakage in the intake manifold; issues with the idle control module in the engine's electronic control unit (ECU); 2. Sticking of the engine idle control valve; wear on the insulation of the idle control valve's wiring; clogging of the idle air passage; problems with the engine throttle position sensor; 3. Issues with the camshaft position sensor or crankshaft position sensor; problems or excessive dirt on the engine speed sensor; issues with the idle control program in the engine's electronic control unit, etc.

[LaRobert]

I often encounter the issue of stalling at idle. As an experienced driver, I find it quite annoying. The most common cause is an underperforming fuel system, such as an aging fuel pump or clogged fuel injectors, which prevents fuel from reaching the engine, making it unable to run smoothly. Additionally, problems with the ignition system are not uncommon—excessive carbon buildup on the spark plugs or a faulty ignition coil can cause misfires at idle, leading directly to stalling. Another culprit could be a dirty throttle body, where carbon deposits block the air intake, resulting in insufficient airflow to maintain stable RPM. Sometimes, the idle control valve malfunctions; it manages speed control when the car is stationary, and if it fails, stalling becomes more likely. A weak battery might also contribute, especially in cold weather when voltage fluctuates after startup. Safety first—if this keeps happening, it's best to get a maintenance check promptly and not wait until it becomes dangerous.

[Daryl]

As a novice driver with only a few years of experience, I find that the engine stalling at red lights is really frightening. There could be many possible reasons: the fuel line is clogged with debris, cutting off the fuel supply; the spark plugs are old and fail to ignite, causing misfires; or the air filter is too dirty, preventing air from entering the engine. Carbon buildup in the throttle body is probably the most common issue—cleaning it usually solves the problem. I've also experienced cases where sensors like the oxygen sensor malfunction, misleading the car's computer into making wrong decisions. A faulty idle control motor can also cause frequent stalling. It's advisable to regularly change the oil and perform maintenance to avoid breaking down on the road.

[LaRuth]

Having driven for decades at my age, idle stalling often stems from aging components. Insufficient engine air or clogged fuel lines, like carbon buildup in the throttle body, can cause instability or even stalling. Worn spark plugs easily lead to weak ignition, especially at low speeds. Faulty idle control valves or sensors are also common culprits. Regular maintenance prevents major headaches—I neglected this in my younger days and later spent a fortune on repairs. Now I've learned my lesson: inspecting the engine brings peace of mind.

[MacLena]

Every day during my commute, I worry about the engine stalling at idle, which wastes time. Possible causes include clogged fuel injection systems, faulty spark plugs causing ignition failure, or insufficient air due to dirty throttle bodies. A malfunctioning idle control valve can directly cause the engine to stall. Sensor issues, such as faulty oxygen sensors, can also disrupt the engine speed. It's recommended to first clean the throttle body and check the spark plugs, ensuring proper maintenance of key components to minimize unexpected stalls.