Car shuts off at idle

The check engine light came on about a week ago. A few days ago, the car would shut off when stopped at a stop light/stop sign. It restarts easily and continues to run as long as it is not stopped for too long or the gas pedal is pressed slightly.

My car has 125000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi, thanks for writing in. This is a sign of a failing idle air control valve. This is a unit that regulates the air flow into the engine as it is mixed with fuel prior to being injected into the motor. When this is not working properly, this will cause an imbalanced load of air and fuel to be supplied to the motor resulting in a loss of power or stall as you have experienced. I would recommend having an expert from YourMechanic come to your home or office to confirm a diagnosis on the issue and make or suggest the necessary repairs or replacements.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most common reasons a Ford Expedition engine stalling are the fuel system, the air intake system, or the ignition system. Search our network of RepairPal Certified shops near you to speak with a technician about your issue. Drivers may notice the engine idling roughly, hesitation to accelerate, and…
Common reasons for this to happen:

Low fuel pressure, dirty or defective fuel injectors, or broken fuel pump: The fuel pump is responsible for transferring fuel from the tank to the engine.

The most common reasons a Ford Expedition has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
Fuses – If the car dies while idling but restarts, there`s a possibility that there might be an issue with the fuses of the car. It`s conceivable that one of the fuses has blown. Take each fuse from the box and hold it up to the light.
There are three major causes for a stalled engine: A lack of fuel, a lack of air flow and improper ignition. Running out of fuel is one of the most common causes of engine stalling, but dirty fuel injectors or a plugged fuel filter can also be the culprit. Your engine needs air to run properly as well.
When your engine shuts off when you slow the car down its often as a result of a: Malfunctioning transmission. Low fuel pressure, dirty or defective fuel injectors, or broken fuel pump. Bad oxygen sensor or mass flow sensor.
If the vehicle randomly shuts off while driving or stationary, there is usually an issue with the engine. Typical patterns here are issues with the ignition system, mixture preparation or fuel. A known error here is that the vehicle was refueled with the wrong type of fuel.
Oxygen (O2) sensor

An oxygen sensor monitors and analyzes the amount of oxygen in a vehicle`s exhaust system after combustion. A dirty, damaged or malfunctioning O2 sensor (or sensors) affects the air/fuel mixture, causing the engine to idle rough.

Common culprits include a faulty fuel pump or fuel pump relay. A clogged fuel filter or bad fuel pressure regulator is also common on return-type fuel systems. Another often overlooked problem is the vehicle simply being out of fuel. Sometimes the fuel gauge breaks or is inaccurate.
Some of the most common sensors that lead to engine stalling include the mass airflow sensor (MAF), engine coolant temperature sensor (ECT) and manifold absolute pressure sesnsor (MAP). The idle air control valve (IAC) and exhaust gas recirculation valve (EGR) are also well known for causing engine stalling.
Yes, low transmission fluid levels can cause a car to shut off. This is because the transmission fluid is responsible for lubricating the transmission and preventing overheating. Without enough fluid, the transmission can overheat and cause the car to shut down.
An idle air control valve, also called an idle air sensor control motor, is an electrically operated valve that controls the amount of air that bypasses the throttle plate in cars with a fuel injection system [source: Autozone]. This causes the idling speed of the engine to change as needed.
A PCV valve that`s stuck open will allow too much air to enter the intake manifold, leading to a leaner idling fuel-air mixture. Stuck closed leads to a build up of pressure in the crank case which creates a variety of oil leaks! And this in turn can lead to a range of issues, including a rough idle.
What happens if idle air control valve is stuck open? If your car`s idle air control valve is stuck open, it will cause the engine to idle at a higher than normal rpm. This can lead to decreased fuel economy and increased wear and tear on the engine. In some cases, it can also cause the engine to stall.
The most common reason your car starts then dies immediately is because of a lack of fuel in the engine. This often happens because there is a small amount of fuel in the fuel rail, which helps to start the engine. However, there is no fuel pressure to keep the engine running.
With that said, there could be a clogged fuel filter, failing fuel pump, clogged catalytic converters, an electrical problem, failed sensor, a vacuum leak, a failing ignition coil, bad plugs, or any number of other possible problems, that will cause the engine to stall.
Many modern vehicles are designed with several fail-safes to help protect the engine in adverse conditions. One of this is an automatic shutoff when the oil pressure drops to a certain level, or the oil level drops too low (note that this is not true for all cars). This causes the engine to stall and die.
When your vehicle splutters and eventually stalls it could be a sign that your car needs new spark plugs. The spark plugs, while small, are a critical part of your engine and are what “spark” air and fuel mixture in the engine sending power through your vehicle.
If your vehicle is diesel powered, a dirty diesel engine filter may cause it to stall. A drop in fuel mileage is a sign of a clogging engine filter.
When your vehicle splutters and eventually stalls it could be a sign that your car needs new spark plugs. The spark plugs, while small, are a critical part of your engine and are what “spark” air and fuel mixture in the engine sending power through your vehicle.
The most common and obvious reason your car may start then die is the fuel shortage in your engine. This happens because there`s not enough fuel in the fuel rail, and there`s no fuel pressure to keep the engine alive. The reason isn`t always you forgetting to fill up your gas tank.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

Read Full Q/A … : Car shuts off at idle

Car shuts off, won’t stay running
ANSWER : The most common problem on this vehicle is the fuel pump and fuel pump module. If you remove the rear seat that the fuel pump cover is, on the passenger side. Listen to the fuel pump when it is running and when the car stalls your fuel pump will stop running about three to five seconds before the engine dies. Then you’ll know if the fuel pump is the culprit or not.

You can try and replace the fuel pump module first then replace the fuel pump. However, the fuel pump can short the module out, causing both to be bad and would need to be replaced. If you need assistance with this, feel free to contact a certified mechanic who can diagnose your starting issue firsthand and help you fix it accordingly.

Read Full Q/A … : Car shuts off at idle

My car shuts off while driving and then turns back on multiple times or shuts off after driving and car turns off.
ANSWER : Hi there. Check the alternator and make sure that the wiring it connected tight. Check the battery cables and make sure that they are tight and clean. Look for any loose ground wires to the chassis on the vehicle. If everything checks out to be working correctly, then the PCM may need to be replaced as it may have a battery disconnect condition. If you need further assistance with multiple functions shutting off, then seek out a professional, such as one from Your Mechanic, to help you.

Read Full Q/A … : Car shuts off at idle

My car has a rough idle when I start my car, when I stop at a light my car turns off. Is it the purge sensor?
ANSWER : This may be a result of a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. Since this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

Read Full Q/A … : Car shuts off at idle

Stays idling when I put it in gear, and the car doesn’t move. When forced into any gear without the clutch, the car does not shut off.
ANSWER : Hi there. The clutch may be worn and slipping causing the engine to stay running as the shifter is put into a gear selection. If the clutch was working, when put into gear and let off the clutch pedal, the vehicle will either move or stall out the engine. Check the slave cylinder and see if the return spring has broken off causing the clutch fork to stay engaged. Also the clutch adjuster cable could be out of adjustment or damaged. If the pedal and hydraulic assembly has no issues, then I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your clutch.

Read Full Q/A … : Car shuts off at idle

High idling, jumping while idling, idle air control valve code
ANSWER : Hi there. This can be caused by the issues that you mentioned or a number of other things. You need to make sure all of the connectors are making good contact. I would then need to know what codes are in the computer to know if this is a circuit issue or not. Most of the time, it is not the circuit but instead a vacuum leak.

If there is a vacuum leak, then the vehicle will act like this and the computer cannot control the idle. Most of the time it is a bad hose or an EGR valve that is stuck open. That is the most common cause for this. I typically remove the EGR to check it to feel the diaphragm on the bottom of it to see if it is moving correctly. If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair your car’s idling issue.

Read Full Q/A … : Car shuts off at idle

My car is idling very rough.
ANSWER : The idle air control valve is common for causing a rough idle in many cars, but it sounds like you have already corrected that. Another thing you may also want to check is the crankshaft position sensor. A crankshaft position sensor monitors the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing and other engine parameters. When this is faulty or not working properly, this will cause problems with the ignition system and generating spark transmission to the spark plugs resulting in starting problems, rough idling and other performance issues. You may also want to check the fuel pressure as low fuel pressure can also cause rough or poor idling if the fuel pattern being sprayed from the injectors is not consistent. This can also happen in the case of having dirty fuel injectors which may also interrupt the spray pattern of the injectors. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your car.

Read Full Q/A … : Car shuts off at idle

Skipping engine, rough idle, shuts off during slow down & idle, overheating, white smoke from exhaust
ANSWER : Hi There,
It sounds like you may have a couple of separate issues going on here. Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator.

The rough idle and shutting off at slow speeds may be caused by a dirty or faulty idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Read Full Q/A … : Car shuts off at idle