When you own a car, it is your responsibility to care for it. Many car owners seem to think a car runs on magic dust. You have to continually check oil, gas, coolant, etc., to make sure your car stays fit for a long time.
In modern vehicles, there are many sensors and functions to make your car run smoothly. Having basic knowledge about your vehicle can help you counter a mechanical problem like your car shutting off while driving.
In this article, we will shed light on the reasons why your car turns off while driving so that the next time it happens, you are well-prepared. Let’s go!
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What Causes A Car To Shut Off While Driving?
The most common cause of why a car shuts off while driving is a bad crankshaft position sensor or issues with the fuel system. It can also happen due to a bad alternator, ignition switch, empty fuel tank, or car engine sensor issues.
While this list gives you a hint of the most common signs, it is far from all of them. Here is a more detailed list of the six most common causes of why your car shuts off while driving:
1. Faulty Crankshaft Position Sensor
The most common reason a car dies while driving is a defective crankshaft position sensor. The crankshaft sensor is necessary for your car engine to run on most car models.
You also have a camshaft position sensor on some car models, which the car uses if the camshaft sensor is faulty. A faulty crankshaft position sensor may not cause the vehicle to stop entirely, though.
However, if your car is equipped with a crankshaft position sensor but not a camshaft sensor and you get a trouble code on it, you need to replace it.
2. Faulty Fuel Pump or Fuel Supply System
A fuel pump supplies the engine with the correct amount of fuel. If the fuel pump does not provide the right fuel to the engine, the motor will shut off, and you will be left stranded.
The bad news is there is no bypass for a faulty fuel pump; you have to fix it or buy a new one. Another reason could be that your fuel filter got clogged, so the fuel pump can’t pump fuel through it.
A fuel filter is a small component whose only job is to clean the fuel that goes into the engine. If the fuel filter is clogged, the fuel entering the system will be insufficient, and the engine will shut down. Fortunately, it is easy for you to replace a fuel filter.
Most fuel pumps are installed inside the fuel tank. A little mechanic’s secret is to give a kick with your foot or something similar on the fuel tank when the car shuts off. If the car starts then, there is most likely a problem with your fuel pump.
Be careful not to hit it with anything with an edge, though, because the fuel tanks are made of plastic, and you may make a hole in it – and that is the last thing you want to do!
If your car turns off while driving but then turns back on suddenly, it can often be due to a bad fuel pump.
3. Empty Fuel Tank
Most car owners probably know that you should check your fuel level now and then while driving.
If you have sufficient fuel for your drive, that is perfect, but if your fuel gauge or fuel level sender has gone faulty and does not show the real fuel level in your car, you could have a big problem.
An easy way to try if there is a problem with your fuel gauge or fuel level sensor is to fill 1 gallon (4 liters) of fuel to see if it starts.
4. Alternator Problems
An alternator manages the supply of electricity in your vehicle. If your car suddenly stops running, the alternator may have gone bad. A faulty alternator will cut the power supply to vital car components, and you will notice the lights turning off in the dash or the engine abruptly losing power.
Mainly if your alternator is going bad, you will experience a red battery light on your dashboard now and then.
If your car still has electric power and the starter motor works after it shut off while driving, there is another problem and not the alternator, though.
5. Faulty Ignition Switch
Sometimes, a faulty ignition switch can cause your car to shut off while driving. The ignition switch is located behind the ignition lock and get’s turned when you turn the key to start the car.
Inside this switch, tiny metal plates can build up corrosion and rust. If this happens and one of these plates loses connection, the whole ignition will get switched off.
This will also cause the whole engine to shut off immediately. Luckily this is easy to check if so. When the car shuts down – check if there are still lights/ignition lights on your dashboard. If the dashboard instrument is dead – there is a big chance of a faulty ignition switch.
6. Malfunctioning Sensors
Modern cars have many sensors to optimize the air-fuel mixture for optimal fuel consumption. If one sensor fails and is off, your car engine might die altogether. If you notice that your car shuts off while driving but starts back up after, or if it shuts off when stopped at idle or when slowing down, it could be caused by a faulty engine sensor, which could cause a wrong air-fuel mixture or idle RPM.
Luckily, most of these sensors cannot shut off the engine completely, though. Sensors like the MAF sensor, Coolant temp sensor, and Oxygen sensor could mess with the air-fuel mixture so much that the engine would die.
How to fix a car that shuts off while driving
To fix a car that shuts off while driving, the first thing you should do is check the engine control module for error codes and all sensor data. You also want to make sure there is fuel in the tank and that the alternator is charging.
Here is some more detailed information on how to fix a car that shuts off while driving:
1. Check trouble codes
With older car models, you had to diagnose the car with a multimeter or just common sense to find a problem. Fortunately, modern cars have built-in diagnostic software that detects when there is a problem with one of the engine sensors and then stores a fault code.
This makes diagnosis much easier, and you don’t have to waste time measuring every sensor in your car engine. You also don’t have to guess and replace the wrong parts.
So the best way to find out why your car shuts off while driving is to check these trouble codes in the engine control module and see if there is any stored issue. To read the fault codes, however, you need an OBD2 scanner. You can either buy one yourself, or you can go to a repair shop, and they will read the codes for you.
Continue troubleshooting with the information you received from the diagnostic scanner. For example, if you found a trouble code on the crankshaft position sensor, you want to check the wiring to this sensor and probably replace the sensor.
2. Check Alternator voltage
If you don’t have an OBD2 scanner or can’t find any stored trouble codes, the next thing you want to do is check the alternator voltage with the engine running.
Basically, you just need to start the engine and measure the voltage of the car battery with a multimeter. If you get a reading below 12.5 volts, there may be a problem with your alternator.
Here is a more complete guide on how to test your alternator: How to Test a Car Alternator (5 Steps)
3. Fill the fuel tank
While it may seem obvious that you need to fill up the fuel tank, you may actually be low on fuel even if you don’t know it. Low fuel can cause the engine to stall when cornering at higher speeds because the fuel pump will suck air instead of fuel.
There is also a risk that the fuel gauge sensor in your tank is faulty, and your fuel level is low even though your fuel gauge says it is full. So this is definitely something you want to check by opening the fuel cap and adding a little fuel.
4. Check fuel pressure
Low fuel pressure is another thing that can cause your car to shut off while driving and so you want to check the fuel pressure in your car. The best way to check fuel pressure is to connect a manual pressure gauge to the fuel rail or line.
You can also use a diagnostic scanner to measure the pressure from the vehicle’s pressure sensor if there is one, but there is always a risk that this sensor is bad. Check the fuel pressure specifications for your car and if you notice that the fuel pressure is low, you need to inspect the fuel filter, fuel pump and fuel pressure regulator.
5. Check the Tachometer
The RPM meter or so-called tachometer on your dashboard receives the information from the crankshaft position sensor in most car models.
If you notice that your tachometer does not work when your car shuts off while driving, or if it does not move when you start the engine, it could mean that there is a problem with the crankshaft position sensor or camshaft position sensor.
6. Check Dashboard
The next thing you want to check is the lights on your dashboard when your car shuts off. If you notice that the lights on the dashboard turn off when the car engine shuts off, this may indicate a problem with the ignition switch.
But it can also be caused by low battery voltage due to a bad alternator as we discussed earlier. But if that’s the case, you definitely want to inspect both of these things.
7. Check sensor data
If you cannot find any error codes stored in the engine control module, but still have a problem with your car – you need to check data from all car engine sensors.
To check this data, you need a diagnostic tool compatible with your car’s engine control module. It can also be quite difficult to know what readings these sensors are supposed to give, so you will first need to obtain a repair manual or the specifications of your vehicle.
8. Talk to a Professional
If you’ve tried everything above but your car still shuts off while driving, it may be wise to seek the help of a professional. Although it may cost a lot of money, it may be wise to get help from someone who has dealt with this issue many times before.
It’s also not certain that it will be more expensive to have a mechanic take a look at it, if he can locate the problem quickly and accurately instead of replacing the wrong parts.
Frequently Asked Questions
Can low oil cause a car to shut off?
Low engine oil levels do not usually cause your car to shut off while driving. But if it’s so low that your oil pressure is getting low – the car may turn off the engine for safety reasons. However, this is often only in newer cars.
Can a bad battery cause a car to shut off while driving?
A bad car battery rarely causes the engine to shut down because the alternator provides the power required. There may be such a short circuit in the car battery in some rare cases, so it will shut down though.
Why does my car keep cutting off when I stop?
If your car shuts off after you stop, the engine is very sensitive at idle. This can be caused by many things but is usually caused by a lean fuel mixture, causing the idle RPM to drop too low. A faulty throttle body can also cause this.
Why did my car shut off while driving and won’t start?
If your car shuts off while driving and it won’t start, it is often caused by a faulty alternator or low fuel pressure caused by the fuel pump. However, many things can cause it, and it needs to be diagnosed with a diagnostic scanner.
Conclusion: Car Shuts Off While Driving
A car that shuts off while driving can be really annoying as the problem can be hard to pinpoint sometimes. Fortunately, modern cars have built-in diagnostic systems that can be used to find out what is wrong with your car. Therefore, you should always start by reading the error codes with a diagnostic tool before diagnosing your car further.
The most common reasons a car shuts off while driving include:
- Faulty Crankshaft Position Sensor
- Faulty Fuel Pump or Fuel Supply System
- Empty Fuel Tank
- Alternator Problems
- Faulty Ignition Switch
- Malfunctioning Sensors
I hope this guide helped you with your car problem, and if you went through this article carefully, I’m sure you should find a solution for your car.