Having your car malfunctioning while driving can be dangerous and uncomfortable. It is a very annoying experience that some people experience when they are least expecting it. If your car breaks down in the garage or in the parking lot, at least you can take a look and ask for help.
But if your car shuts down while you are driving on the highway, it can be incredibly dangerous for you and other drivers. Numerous factors might cause your car to shut down all of a sudden. Sometimes, your car might even turn back on, which is more confusing.
Summary
The most common reasons a car turns off while driving but turns back on are dirty fuel injectors and an empty tank. However, another common reason a car turns off while driving includes a faulty ignition coil.
In this article, we’ll also explore other topics, like the following:
- What will it cost to fix?
- How to fix the issue
We want to help reduce that confusion. Take a look below and learn about 15 possible reasons why your car turns off while driving it down the highway.
Table of Contents
- Reasons car turns off while driving
- The car stopped running while driving and won’t start.
- The car turns off when stopped at a light.
- The car shuts off when stopped or slowing down.
- The car turns off while driving but turns back on
- How to fix a car that randomly dies while driving
- FAQ
Reasons car turns off while driving
From a dead car battery to a faulty engine control unit, there are many reasons why your car might shut off while driving. Let’s take a look at them and explain these problems in detail.
1. Faulty spark plug
If the spark plugs are dirty or broken, your engine might suddenly stop running. This component is situated at the top of the cylinder head and is an important part of your vehicle’s engine. If a faulty spark plug is the cause of the problem, you will have to replace it as soon as possible.
Most likely, you already know how this spark plug works. However, you should also pay attention to its condition and maintain it properly. If spark plugs are clean, your car’s fuel efficiency will improve. You can reduce costs in the long run.
But if the spark plug is broken, your car will stall when idling or even driving. Remember that these parts are exposed to a lot of stress and can wear out over time. If you have high mileage on your vehicle, consider checking with a mechanic and having them inspect all of the components.
Did you know the spark plugs can be made from 4 different materials? They are:
- Copper
- Silver
- Platinum
- Iridium
Those made of Iridium are the most expensive ones, and they sell for way over $100 a piece.
2. Dead car battery
Checking the battery’s health is worth considering if you encounter problems while driving. It is one of the most common causes for the engine shutting down, although there are many more things to consider. Whether you drive a Chevy or a BMW, car batteries can always malfunction.
Sometimes, your car will continue draining power even if the engine is shut off. It is called a parasitic drain problem and can occur if you start up a sitting car that has been unused for long periods.
To avoid this problem, cut all power to the radio and internal components when leaving the car. Some of them can waste power even after you park and turn off your car. In time, this will lead to rapid drainage of the battery, which will eventually completely die.
3. Faulty ignition coil
Just like spark plugs, the ignition coils are important for the optimal functionality of your vehicle. If you have a faulty ignition coil, your car might suddenly shut off while driving which can have disastrous consequences.
This component is situated above the spark plug. It is responsible for creating a charge to ignite the fuel in the cylinders. If your car stalls often, an ignition coil may be bad or failing. But the symptoms of this problem will vary from model to model.
The ignition coil has an important role in your vehicle, and it’s process of operation is described in this table which makes it easier to understand.
| Step | Operation |
| 1 | Voltage from the car’s battery is converted to high voltage necessary to ignite the fuel |
| 2 | The ignition coil produces a magnetic field through the primary winding once it receives low voltage power |
| 3 | A high-voltage pulse is generated and sent to the coil through its secondary winding |
| 4 | The magnetic field collapses |
| 5 | Spark plugs receive the high voltage power in order to create the spark necessary for igniting the fuel |
In some cases, you might need to replace the ignition coil. Getting them tested at an auto shop is recommended, so you know how much work is required to change them.
The car stopped running while driving and won’t start.
Sometimes the car stops running, and you get lucky afterward when you turn it back on. But in some cases, it happens that the car cuts off all the power. You can no longer start it again. You will have to call the towing services and have them take your car to the nearest auto repair shop.
4. Faulty ignition switch
A faulty ignition switch can also be responsible for randomly stopping your car. The ignition switch will fail to turn on the electrical components in your car if it is broken. It is a serious problem, and you should seek a solution as soon as possible because a faulty switch will cause significant electrical problems.
You might lose the use of the radio and door locks. However, your safety is also at risk when the headlights or airbags completely stop working. If the car stopped on a deserted road in the middle of the night, you might have to wait in darkness for help to arrive.
5. Faulty alternator
The alternator is what keeps your car’s battery charged. Therefore, your battery’s life directly depends on this component. If your car dies while driving, you might have to consider the possibility that the alternator fails to provide enough charge for all of the electrical components in your vehicle.
Older models will struggle with keeping up with an increased charge. If you haven’t changed your battery in a long time, this component might be failing too. For example, the failure of the odometer control module will drain the battery and ultimately shut off your engine.
It is a device that sends signals to your car’s computer. While the cause is not directly related to the problem, it is important to trace it back to its source.
6. A faulty crankshaft position sensor
It is a relatively cheap part that has the purpose of sending signals to the engine control module. It regulates the timing of the ignition and fuel injector flow.
When this signal is no longer provided, the control module of your car will try and recycle the ignition. It ends up in your car shutting off. This component can wear and break easily as time passes. But metallic contamination should also be considered, as many drivers reported this to be the cause of their problem.
Excessive wear of the crankshaft position sensor causes rapid deterioration. It requires you to change this part more often to avoid complete failures.
The car turns off when stopped at a light.
Nobody wants their car – or someone else’s – to suddenly stop working at a stop light. When the light turns green and your engine stalls, that can be considered a worst-case scenario for some drivers.
The symphony of car horns from the traffic behind will not make your day better, so let’s look at 3 more possible causes why your car might suddenly stop working.
7. Faulty MAF sensor
Each part has its purpose and functionality within your car. When all of them work together, you are able to enjoy a smooth ride and arrive home safely. The MAF sensor controls the air intake into your engine. If this component fails, your car will eventually stall while driving.
There are more symptoms of a faulty MAF sensor. It includes a fuel consumption much higher than normal or a sudden misfire in one of the cylinders. Replace the MAF sensor as soon as possible after you have identified this component to be the cause of your problem.
What to look for in a failing MAF sensor:
- Excessive vibrations when stationary
- RPMs changing without your input
- Engine runs either rich or lean
- The check engine light comes on
8. Faulty MAP sensor
MAP is short for manifold absolute pressure, measured by a specific sensor. This sensor will measure the atmospheric pressure in the intake manifold when it works properly. However, a faulty one will suddenly cause your car or truck to stop working.
The engine management system will calculate the fuel injection and air mass flow whereas the MAP sensor sprays gas into the intake manifold through a small hole on one of its ends. As more or less air gets absorbed, the MAF sensor changes instantly.
Both parts should be in perfect working condition to avoid problems such as the engine suddenly stopping working.
9. A faulty engine control unit
Another cause for this problem might be related to the engine control unit. This component receives signals from all the sensors installed on your car. With this information, the ECU will adjust to the driving conditions as they change.
If this component is broken, it will shut down the engine to avoid overheating. While it saves the car from further damage, it can also prevent it from starting again until you solve this problem.
The car’s electrical system might still be working, and you can even notice the lights coming on when you turn their position. It will come in handy if you are stranded on the side of the road at night.
Here are the most common reasons for a faulty engine control unit:
- A short circuit
- Failure caused by continuous vibrations
- Temperature influence
The car shuts off when stopped or slowing down.
Your car can also shut off when you are stopped or while you are slowing down. This scenario is safer than the one where you are cruising down the highway at high speed. If the car shuts off when you are already stopped, you have more flexibility to investigate the problem.
10. Faulty throttle body
It is a part that supplies the right amount of fuel and air to your engine. Because it controls how much power the engine produces, a faulty throttle body will cause the car to shut down completely while you are slowing down.
Situated between the gas pedal and the engine, the throttle body lets more gas and air into the combustion process as you press down on the gas pedal. If this component is faulty, one of the most vital operations in your vehicle cannot be completed and your car will shut down.
Here are issues the component will face issues:
- Buildup that causes air flow issues
- Carbon
- Filth
11. Clogged air filter
The air filter must be clean and free of debris to function properly. If it is clogged, it will cause your car to shut down while you are driving. You should check the condition of this filter from time to time and maintain it properly to ensure a long life.
For some reason, most drivers ignore this component and forget about their filter until it’s too late. Cleaning and maintaining your air filter will cost you less than $100 every couple of months.
When the air filter is clogged, you will notice some obvious symptoms that will get your attention. These symptoms are presented in the table below.
| Symptom #1 | Your engine misfires often |
| Symptom #2 | The check engine light turns on |
| Symptom #3 | Dirt becomes noticeable on the air filter |
| Symptom #4 | Significant reduction in horsepower |
| Symptom #5 | Black smoke from the exhaust pipe |
12. Faulty fuel pump
The electrical system of your vehicle powers up when you turn the key on. A signal is sent to the powertrain control module, which allows this system to start working. But when you hit the start button, the fuel pump must create enough pressure to facilitate fuel transition from the injectors towards the rail.
If the pump cannot create enough pressure, the injectors will not be able to work properly, and the engine will shut down. It is a critical problem, and you should fix it as soon as possible.
Here are the most common reasons for a faulty fuel pump:
- contamination
- overheating
- wear
The car turns off while driving but turns back on
In some rare cases, the car might turn off while you are driving but then suddenly turns back on. You can consider yourself lucky because now you can continue your drive – although this is not recommended since it can always happen again.
13. Empty fuel tank
Sometimes you might forget to look at your dashboard during long and smooth drives. In this case, there is no serious problem with your car. The only reason it stopped working was that there was insufficient fuel in the gas tank.
Some analog systems might malfunction and show an incorrect fuel quantity on your dashboard. You should replace this indicator and pay more attention to your fuel levels.
14. Dirty fuel filter
The fuel can be full of contaminants, but they get filtered out by the fuel filter. However, this filter can get dirty over time and cause many problems to your engine. When it gets dirty, the flow of gasoline is restricted, and your car will not receive the optimal quantity of fuel.
In some cases, the fuel pump may fail and cause similar problems. However, the engine still has power and will continue to run for a while. Either way, you should also check the fuel filter when looking at the air filter.
15. Dirty fuel injectors
A dirty fuel injector will stop the fuel flow and cause your car to stop working. Your vehicle needs a specific amount of fuel to be delivered every moment. A single drop of dirty fuel can ruin the entire system.
Clean the fuel injectors when you take a look at other components. Over time, they can get dirty and cause many problems, with some of them being irreversible.
How to fix a car that randomly dies while driving
Once your car randomly stops running, there are some things you must do to ensure your safety and the integrity of your engine. In some cases, you might succeed in restarting the car. Follow the steps below:
- Step 1: Drive and stop the car on the side of the road. Coast the car and slowly pull over to the side where you can avoid the traffic that is coming from behind.
- Step 2: Try to restart the car. If you succeed, continue driving towards the nearest auto repair shop. Do it at a low speed and don’t enter busy roads.
- Step 3: Turn on the emergency flashers. It will signal other drivers that there is a problem with your vehicle. They will have time to react with increased awareness.
- Step 4: Call for help and contact towing services. They will be able to tow your car to the nearest repair shop in a safe way.
FAQ
The alternator is always working harder when the battery cannot perform well. But an overworked alternator will cause more problems that lead to your engine turning off.
The first thing you should do after the car stops working while driving is to apply the brake and gently steel over the side of the road. Turn on the hazard lights and ask for help.
If your engine stalls often, you are a risk to other drivers when taking part in the traffic. Your car can suddenly stop working, and in some cases, you might not be able to steer to the side of the road. Your priority is to get this problem fixed as soon as possible.
