I had a problem with my car where it would randomly shut off while I was driving. The only way to get it back running is to pop the hood and disconnect the battery for 10 or 15 minutes. Then, reconnect everything and start over.
What causes this, and what can be done to fix it? The most likely cause would be the ignition control system in front of the driver’s side strut tower. A known design flaw in most modern cars is that they will intermittently go on the lean fuel mixture.
When this happens, it will cause a temporary no-start condition until the problem can be isolated and repaired. This is due to a secondary air system in the intake manifold, which provides oxygen during cold engine start-up conditions.
Let us see other potential reasons for cars shutting off while driving:
Car Shuts Off While Driving Reasons
If your internal combustion engine shuts down while driving, then it might be due to the following reasons:
- Faulty Fuel Pump
- Empty Fuel Tank
- Dirty Fuel Filter
- No Fuel Injection
- Faulty Throttle Body
- Clogged Air Filter
- Bad Crankshaft Position Sensor
- Faulty MAF Sensor
- Faulty MAP Sensor
- Faulty Engine Control Unit
- Faulty Ignition Switch
- Faulty Alternator
- Faulty Spark Plugs
- Dead Battery
- Faulty Ignition Coil
All these potential reasons can be classified under 4 main categories. Let us see these reasons in detail.
1. Fuel is not reaching the combustion chamber.
Faulty Fuel Pump
If the engine shuts off suddenly while driving, it is more than likely caused by a bad fuel pump. When you turn the key on, all electrical items receive a signal from the PCM (Powertrain Control Module), which allows them to work.
When you hit the start button, this tells the fuel pump that it is time to go, and it must create enough pressure to push fuel through your fuel injectors and out of your rail.
If your bad fuel pump does not create enough pressure, your injectors will not receive the proper amount of fuel, and your engine will shut off. You may have heard this referred to as a “stumble.”
It isn’t harmful to drive around for a few minutes with the stumble, but you should get it fixed as soon as possible because it can lead to damage to other parts.
Empty Fuel Tank
Yeah, this has happened even to the best of us. The car shuts while starting, and we start looking for potential causes upside down. It was shut off in the actual because there was no fuel in the gas tank.
If there is no fuel in the fuel system, how come it will work. Sometimes due to a faulty gas gauge, we cannot keep track of the actual amount of the fuel. This leads to no fuel in the fuel tank while we are unaware.
You must repair or replace the faulty fuel gauge to avoid this scenario.
Dirty Fuel Filter
A dirty fuel filter may lead to a car shut down. The fuel filter’s job is to filter out the contaminants in the gasoline. When the fuel filter gets dirty, it restricts the flow of gasoline (and air), which means that your car doesn’t receive as much “gas” (air-fuel mixture) as it needs.
This can lead to car stalling or an engine that won’t start at all. There are some cases where the fuel pump itself may fail, causing similar problems. In these cases, the engine will run but not well enough to keep running as long as it normally would.
Dirty Fuel Injectors
Car shuts down while driving due to no fuel injection from the fuel supply line. The most likely cause is a dirty fuel injector. Fuel-injected cars require precise amounts of fuel to be delivered by the injector at the right moment.
If even just one drop of dirty gas is pumped into an injector, it can clog up all of the holes causing your car to die. The most common side effect of the dirty fuel injectors is that the car starts and runs for a few minutes, then quits.
The car may have been sitting for a while. Gas has evaporated from the fuel supply line, and if you start it without first putting more gas in, the engine could stall.
But in most cases, you would need to clean the injectors in order to get your car up and running again.
2. Air delivery to the car engine is not sufficient.
Faulty Throttle Body
A faulty throttle body will cause your engine to shut down while driving. It is a car engine part that is responsible for supplying the right amount of fuel and air to your engine thus, it controls how much power the engine produces.
The throttle body sits between your gas pedal and your engine. When you push down on the gas pedal with your foot from inside the car, it signals the throttle body. The throttle body then opens up and lets more gas and air into the combustion process, which sends more power to your engine.
A throttle position sensor, or TPS for short, is also located in that same general area of your car’s engine. It is an electrical device that sends information to your car’s main computer system.
The TPS tells the car’s computer if you give it more gas or take some away. If the car senses that there is not enough gas, it will automatically shut off so as to avoid damaging the engine.
Clogged Air Filter
A clogged air filter will shut down your car while you are driving. That’s why it’s important to ensure that your engine air filter is clean and working properly. If properly maintained, an engine air filter should last the vehicle’s life.
Yet as any experienced auto technician or even car owner knows, most people ignore or forget about their engine air filter until it becomes so clogged that it noticeably reduces their vehicle’s performance.
How often you should change your engine air filter and how much it costs will vary based on the size of the engine and the type of vehicle, but it is a service that can typically be performed at your local repair shop for less than $100.
3. Some sensor in the electronic system is malfunctioning.
Faulty Crankshaft Position Sensor
A crankshaft position sensor is an inexpensive part that can fail intermittently, leading to a stalling condition. Normally the crankshaft position sensor (CPS) sends a signal to the Engine Control Module (ECM), telling it if the engine is turning, which lets it control spark, fuel injector flow, and ignition timing.
When this signal disappears, the ECM will attempt to compensate by recycling the ignition, but this will eventually run out of control, and your engine will stall.
A crankshaft position sensor can break or be contaminated with metallic particles that cause it to fail. It may also wear out over time.
The crankshaft position sensor is located on the back of the crankshaft, so when it does start to deteriorate, it will commonly be because of excessive wear in this area. This could happen because of a failed thrust bearing or through excessive engine revving over time.
Faulty MAF Sensor
This part controls how much air is let into the engine. If this component fails, it will cause your car to run erratically or even stall completely while driving. Here are some other symptoms you might encounter if the mass airflow sensor is bad:
- The idle speed increases on its own.
- If there’s a misfire in one of the cylinders, this could be caused by the mass airflow sensor.
- The car will surge or change speeds erratically.
- Fuel consumption is much higher than normal.
If the mass airflow sensor becomes faulty, you will need to have it replaced as soon as possible to ensure safety when driving your vehicle.
Faulty MAP Sensor
If your car shuts down while driving, make sure to check to see if there are any issues with your manifold absolute pressure sensor. The job of a manifold absolute pressure sensor is to measure the atmospheric pressure within the intake manifold.
The signal is then used by various systems, including an engine management system to calculate air mass flow and fuel injection.
The manifold absolute pressure sensor is vacuum tubing, with a small hole of around 1mm diameter on one end. This hole sprays gas into the intake manifold that absorbs an oil film within the tube. The engine’s air mass flow changes minutely as more or less air gets absorbed by this film.
Faulty Engine Control Unit
Your car may shut down while driving due to a faulty engine control unit. The air control unit (ECU) receives signals from various sensors. The car will not adjust to current driving conditions if it goes bad.
For instance, the ECU coolant sensor is responsible for measuring engine temperature, and if faulty, it will shut down the engine to avoid overheating, thus saving the car from further damage.
Other sensors that you should look out for are a faulty crankshaft position sensor, oxygen sensor, throttle position sensor, mass airflow sensor, manifold absolute pressure sensor.
If the ECU wrongly misinterprets readings from any of the faulty sensors, your car may experience shutting off while driving.
4. The car’s ignition system is not working.
Faulty Ignition Switch
If your car shuts off while driving, it might be due to a faulty ignition switch. That’s what happened to me. After I got home and checked my car for anything else wrong, I noticed the ignition switch was not working; it couldn’t turn on or off any of the electrical components in my car (such as interior lights, radio, dashboard).
The faulty switch can cause a variety of electrical problems. Your car may have issues with the airbag system the power door locks, and you might even lose the use of your stereo or headlights. You may be stranded on a dark road waiting for a tow truck to arrive.
You should have the ignition switch replaced as soon as possible to eliminate this potential danger.
If your car shuts off while driving, it might be due to a faulty alternator. The job of an alternator is to keep your car’s battery charged. The more electrical components you have on your vehicle, the more load you’ll put on the alternator.
If too many electrical devices draw power from it, the battery will eventually drain and shut off your engine. The battery can die, too. If the battery is old enough, it might not be able to hold a charge.
However, some electrical devices can cause your car to shut off abruptly. If you drive an older model vehicle with an analog odometer, then the device called the “odometer control module” has probably failed.
It sends faulty signals to your car’s main computer, which regulates how much power is drawn from the alternator. This can cause the battery to drain and shut off your engine.
Faulty Spark Plug
Your engine may stop running due to dirty or fouled sparkplugs, usually located at the top of the cylinder head. There is no fuse for this component, so your car will not start unless you can repair the problem yourself or have it repaired by a mechanic.
The spark plug is part of the ignition system and consists of a metal electrode surrounded by a ceramic insulator. The electrode heats up and creates an electrical current that travels through the wires to the distributor and eventually to each cylinder in your car. The current ignites fuel within each cylinder, producing power that moves your vehicle down the road.
Clean spark plugs improve your engine’s fuel efficiency because the cylinders are firing properly. A dirty or fouled spark plug does not allow a current to flow freely, so the car will stall when idling or driving.
If you have a high mileage vehicle that has never had its ignition system serviced, it may be time to clean or replace the dirty spark plugs. You can perform this service yourself with a few tools or call a professional to do it for you.
Dead Car Battery
If your car is shutting off while driving, make sure to check the battery’s health. If the cause is not a faulty battery, it might be excessive parasitic or “Vampire” loads.
If your car’s battery dies frequently or has trouble starting up after sitting unused for long periods of time, you may have a parasitic drain problem. This means that something in your car is draining power even when the engine is shut off.
Some of the most common sources of the parasitic drain are stereo memory settings. Cut all power to these items when you exit your car. If your radio does not turn off by itself, you can leave it on and change the radio’s clock display always to display “0000” instead of time or date. This will ensure that no numbers are constantly spinning, wasting power.
Faulty Ignition Coil
Your car may shut off while driving due to a faulty ignition coil. The ignition coil is a crucial component in the ignition system. The ignition coil is a small component that fits over the top of your spark plug.
It creates a high voltage charge to ignite the fuel in your engine’s cylinders. If you’ve been experiencing problems with your car shutting off while driving or a misfire, then an ignition coil may be bad and failing.
As you may imagine, the symptoms of a faulty coil may vary from model to model and engine size. You may need to replace the ignition coil in your car if it’s has a broken coil or is not being recognized by the engine computer.
You can have your coils checked out to see if they need replacement. It costs money to have them tested, but you know how much work will be required when changing your ignition coils.
How To Avoid Car Shutting Off While Driving?
To keep your car running, you must follow the proper car maintenance schedule. It is the only pro-tip to avoid any problems.
- If your car is having trouble starting up, it may indicate that there’s a problem with either the fuel pump or the fuel filter.
- Replace your faulty spark plugs if they are worn out, broken, or have gaps between their electrodes. Also, make sure there is at least a 0.8mm gap between each electrode as worn-out spark plugs often lead to engine misfires and stalling.
- Check the ignition coil and distributor cap as they may be faulty. Worn out, broken, or improperly installed ignition wires can also lead to engine misfires.
- A faulty or defective fuel pump relay may cause the car to stall while driving in lower gears.
- If the gasket of the gas cap wears out, then your car’s fuel efficiency will reduce.
- If you notice road vibration causes your car to lose power, a loose engine mount may be the cause.
If your car shuts off while driving, you should not ignore this matter. This could be a sign of a very dangerous problem in your engine. If you choose to ignore this issue when it happens, you might end up with expensive repairs. Some signs will help you understand if your car is shutting off while driving.
If your Check Engine Light or Service Engine Soon Light comes on, or one of the other warning lights on your dash starts flashing, you should bring your car into our shop immediately.
If the engine starts to lose power while driving, you should try to get off of the road and into a safe place as soon as possible. If you are able, start turning things off in the vehicle that could be causing extra strain on the electrical system.
Do that if you can shut off the radio or turn down the lights. If the problem is with your engine rather than electrical, try shifting into Neutral.
If your vehicle is blowing black smoke from the tailpipe, this could be a sign of other major problems as well. You should have the vehicle looked at right away.
Car shutting off while driving is just a sign the root cause is something else. You should try to find that out as early as possible.
Frequently Asked Questions
What should you do if your car suddenly shuts?
If your car shuts off while driving, here are some steps that will help.
First, try turning the key in the ignition again and see if that starts things up. If not, that means your battery is dead or low, so don’t try cranking it.
If turning the key in the ignition does not restart the car, leave the headlights on, apply the emergency brake and call for assistance using your cell phone or roadside assistance number.
If your car shuts off while driving, do not brake heavily or turn the steering wheel abruptly. If possible, it is best to use low gears and coast to a stop. If it is nighttime, turn on your emergency flashers.
How long can you ignore engine stalls?
It depends upon the severity of the symptoms. If symptoms are mild, you may be able to safely drive for days, weeks, or months with an engine misfire until it finally stalls out. But as a car owner, you will have to face your fears and take your vehicle to a qualified mechanic at some point in time.