No one enjoys it when their car breaks down. It disrupts your day and can cost a lot to fix: If your car shuts off while driving, it’s also quite dangerous.
Your steering and brakes need more force, and you could get stranded in the middle of the road far from help.
If you’re trying to answer, “Why does my car shuts off while driving?” You’ve come to the right place. Many factors can play a role. It might be a quick, easy fix or an extreme case where you’re facing days without your vehicle.
Gasoline engines need three main things to run: air, fuel, and spark.
By looking into each system, we can find out what’s causing your car’s problem and get you back on the road.
Air Intake System
All combustion engines require air to run. If something clogs airflow, the engine might turn off while driving.
The intake system brings air into the engine through an air filter, a mass airflow sensor, and a throttle body. If any of these three parts aren’t working, your car could shut off while driving.
Replacing air filters is part of regular car maintenance. They can get dirty and not allow air to flow in the way the engine needs.
Check the filter and its housing for large obstructions preventing airflow. Most people can inspect this in minutes with very few tools.
Mass Air Flow Sensor
The Mass Air Flow (MAF) sensor tells the engine about the air that is about to pass into it to ensure it provides the proper air/fuel mixture.
This sensor is less likely to cause the engine to abruptly shut off while driving. It could cause issues while idling, cause your car to run inefficiently, or show a check engine light (CEL).
If your dashboard shows a check engine light, start by having that checked. Some auto parts retailers allow you to check your own for free, or you can bring it to a mechanic for professional assistance.
The final component of the air intake system is the throttle body that controls how much air goes into the engine. It could be a reason why your car turns off while driving.
If you experience rough idle problems, the throttle body might be dirty. Cleaning your throttle body might fix issues that could cause your car to shut off while driving.
Fuel System: Why Does My Car Shut Off While Driving?
If you don’t find any problems with the air system, then the fuel system is another good place to look for problems. When the fuel system isn’t working, you could experience your car turning off while driving.
Out of Fuel
It might seem simple, but running out of fuel is a reason why cars shut off while driving. Maybe you’ve been too busy with work, or your fuel gauge isn’t working, but it can happen to anyone.
If your car shuts off while driving, make sure it has enough gasoline (or diesel) in the tank. Don’t trust the gauge to tell you that it’s full. Add a small amount (at least one gallon or four liters) and try it again.
Your low fuel light should illuminate when about 10% is remaining. It’s a good idea to fill up when you see that light come on. During winter or when driving in remote areas, you should keep your fuel tank topped off to avoid disastrous situations.
If you are regularly running out of fuel, check out Gas Buddy to find fuel locations closer to you. And set a reminder on your phone to fill up before it runs out!
Clogged Fuel Filter
Just like an air filter, you should replace your fuel filter regularly. It is part of routine maintenance on most vehicles. When a fuel filter gets clogged, it could result in your car turning off while driving.
If this happens to you, see if you can check your owner’s manual to see how often you need to replace the fuel filter. If overdue, get it replaced.
Some fuel filters are accessible and easy to replace. Others are inside the fuel tank and usually require professional assistance.
Fuel Pump Failure
Fuel doesn’t magically drop into an engine. The fuel pump pushes it through. If the pump isn’t working, it might not provide enough fuel to the engine. And your car could shut off while driving.
You can follow this YouTube video to test the pressure of your fuel system. If it’s too low, you might have a bad fuel pump that needs replacement.
Electrical and Spark Problems
We’ve now gone over the air and fuel systems. The final element to inspect is the electrical system. It provides the spark for combustion (in gasoline engines). It also maintains a system of sensors and switches to keep almost any combustion engine running.
If you’ve had your car shut off while driving, start to inspect the electrical system by checking the voltage of your battery. This will tell you if your alternator is running well or needs replacement.
A basic voltmeter is the only tool you need to perform this test. Some auto parts stores might be able to help you test your alternator as well.
While your car is on and idling, shut on all the electrical equipment. This includes headlights, interior lights, radios, and other accessories. If the voltage drops below 13.5V, your alternator shows signs of failure.
Sometimes a failing alternator will show signs before your car shuts off while driving. These include things such as dimmed lights, a battery warning light on your dashboard, or problems starting. But other times, it can result in your car suddenly shutting off while driving.
Bad Crankshaft or Camshaft Position Sensor
An engine has many sensors to keep it running at its best. But two of the most important ones are the crankshaft position sensor and the camshaft position sensor.
The crankshaft position sensor helps tell the vehicle when to provide ignition based on the engine’s RPMs and relative speed. If it goes bad, your car might turn off while driving.
Likewise, the camshaft position sensor is a vital piece of the electrical system. It tells the vehicle which cylinder is firing so it can run. If you’re trying to find an answer to why your car shuts off while driving, this could be your culprit.
Faulty Ignition Switch
A faulty ignition switch is a common cause of your car shutting off while driving. The engine relies on the ignition switch to tell it that the key is in and turned on; otherwise, it won’t run. It’s a safety feature that makes it so people can’t take your car without the key.
But when the ignition switch goes bad, it might tell the car to shut off while driving. These can be difficult to diagnose. If you’ve noticed that your vehicle sometimes starts when you put your key in and sometimes doesn’t start at all, this might be the problem.
Other Sensors or Electrical Issues
There are a variety of other sensors and electrical issues which could cause your car to shut off while driving. Bad oxygen sensors, failing coolant temperature sensors, and faulty engine control units cause your car to shut off while driving.
If you have a check engine light, this can help diagnose these types of problems. Other times, such as in cases of a faulty ECU, diagnosis can be challenging and will likely require a professional to diagnose and repair.
To figure out why your car shuts off while driving, check the air, fuel, and electrical systems. If any of these are faulty, your vehicle will have issues driving.
You can perform many checks on your own if you’re a bit handy. Inspect the air filter, clean the throttle body, and test the fuel pump. Bring it to an auto parts store for help checking the codes related to a check engine light. They can also test the alternator.
And if none of those work, it’s time to find a professional to look for other issues to help you solve why your car shuts off while driving.