Car Dies While Idling but Restarts Later: What Are the Reasons?

Like every other mechanical structure, an automobile is also supposed to have troubles due to issues with one or multiple components. One such particular problem is car dies while idling but restarts later. There could be numerous reasons for the engine to fail to maintain power at low speeds. You may need to seek professional help because it sometimes needs special expertise to troubleshoot this particular complication.

Car Dies While Idling but Restarts Later: The Reasons

It is quite irritating when your car shuts off while idling, especially when you are at the traffic signal. It’s difficult to pinpoint the exact reason without the help of an expert mechanic. However, you can still look into some specific areas to spot the source of the trouble.

1. Fault in the transmission

This particular problem is unique to automatic transmission vehicles. The manual transmissions have a manual clutch for transmitting power. An auto gearbox has a torque converter instead to do this task. If it is cracked or damaged, or the fluid level in the transmission becomes low, the vehicle will die at the time of idling. A broken torque converter solenoid can also be the culprit.

Defective auto transmission can cause this problem.
Defective auto transmission can cause this problem. (Photo:

2. Clogged fuel filter

To have the cleanest fuel before the fuel enters the engine, it will have to go through the fuel filter to remove all impurities and dirt… Therefore, over time, this fuel filter is also prone to damage and gets stuck. Therefore, you should clean and change the fuel filter periodically.

If for a long time, your fuel filter is not cleaned or replaced, it will become clogged. This makes the fuel unable to reach the fuel pump to enter the engine, causing a sudden shutdown of the vehicle, especially a car that is suddenly stopping. 

If the car dies while idling but restarts later, drive the car up and down a steep road to see if the problem persists. If the car still stalls, it is certain that the source of the problem is a blocked fuel filter. You can easily replace it though and it is pretty cheap too.

3. Fuel pump and fuel injectors

A broken fuel pump cannot properly transfer fuel from the oil tank to the engine, causing the fuel pressure to reduce. The inconsistent oil streaming to the engine does not cause any issues at high speeds but cannot keep it running at low speeds or while idling. A malfunctioning fuel pump is often difficult to detect. But if the pump is faulty it makes the car engine noisier than usual.

On the other hand, dirty fuel injectors either do erratic spray or no spray of oil at all, causing the stalling of vehicles while idling. Although the fuel is clean before entering the injectors, over time, the injectors will still be dirty and it will cause the injector to be clogged and blocked. When the injectors are clogged, the fuel cannot enter the combustion chamber. Spray flow and injection timing are not correct. This greatly affects the combustion process.

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4. Defective mass air flow sensor

The sensor provides the engine with the quality and quantity of the air that goes into the motor. Based on that information, the Engine Control Unit (ECU) decides the amount of oil to be sent to the engine. The airflow sensor will give incorrect readings if it is defective or dirty, causing the car to shut off a problem when idling.

5. Malfunctioning idle air control actuator

car idle air control actuator
The issue with the actuator will result in the car stalling at idle. (Photo:

This component controls the RPMs when the engine is idling. The electronic control unit sends information to the actuator so that it can keep the engine functioning by maintaining the right RPM. If it’s faulty, it does not send any information to the engine, causing it to stall at idle.

6. Faulty cooling system

Failure of the cooling system is one of the causes of an overheating engine, causing the car to stall in the middle of the road. The most common cooling system failure in vehicles is a lack of coolant fluid. When this error occurs, your engine can’t cool down properly. Besides the cause of low-level coolant, the vehicle cooling system can malfunction due to many other causes such as a broken water pump or damaged thermostatic valve… Whatever the cause, just the cooling system having problems will affect the engine operation.

Drivers should handle this situation as soon as they see the warning light on the car dashboard, not until the car stops suddenly while idling or driving, it will be very dangerous. When the coolant temperature is abnormally high, the driver should quickly pull over in a safe location. If the coolant is boiling, let the car run idle, and turn off the air conditioner and electrical equipment in the car to reduce the load. 

Note that when the engine compartment is very hot, be very careful to avoid burns. It is best to wait for the engine to cool down completely and open the hood to check. If the car has run out of coolant, add more fluid. Then take the car to the garage to have the cooling system checked as soon as possible.

7. Issues with the wiring harness

A car dies while idling but restarts later due to misfiring ignition too. If the wires in the wiring harness are corroded or loose, the car will lose voltage because of the unstable connection to the ignition circuit. As a result, the engine won’t have adequate power to stay functioning when the speed slows down.\

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How To Prevent Cars From Stalling While Driving or Idling

To avoid the situation that the car is stalling or turning off the engine at idle you should note that:

  • Check and maintain the engine and related parts in accordance with the vehicle manufacturer’s maintenance schedule
  • Regularly check the car cooling fluid, and refill when almost empty
  • Change engine oil every 5,000 – 8,000 km is recommended (the exact number will depend on your car model)
  • Periodically clean the fuel filter, change the fuel filter every 40,000 km or 2 years of operation
  • Replace new spark plugs after 40,000 – 100,000 km and car injectors after every 20,000 km of operation.