Does your vehicle suddenly shut off while you’re driving, and it’s driving you crazy? We have got you covered!
Modern vehicles have complex systems and functions that keep them running. Knowing a bit about your vehicle can help you with a mechanical malfunction, like your car shutting off while driving. What makes a car shut off while driving?
The main reasons a car shuts off while driving are a faulty crankshaft position sensor and fuel supply issues. A vehicle can also shut off while driving due to a faulty alternator, faulty ignition lock, or running out of gas. There are several reasons why this could happen, so it is important to diagnose it properly.
This list gives you an idea of some common reasons, but it is by no means exhaustive. Here is a more detailed list of the six most common reasons for why your vehicle shuts off while driving:
6 Reasons Why A Car Shuts Off While Driving
1. Bad Crankshaft Position Sensor.
A faulty crankshaft position sensor is the most frequent reason why a car dies while you are driving. A crankshaft sensor is required for most cars to run.
In some cars, you also have a camshaft position sensor, which the car will use depending on whether the camshaft sensor is bad.
Again, a faulty crankshaft position sensor may not stop the vehicle completely; if you have a crankshaft position sensor in your car, and not a camshaft position sensor, and you get a trouble code on the crankshaft position sensor, then you should replace that sensor.
2. Bad Fuel Pump or Fuel Supply System.
A fuel pump elicits the correct amount of fuel to the engine via the fuel injectors. If the fuel pump doesn’t supply the engine with the right fuel, the motor will turn off; you’ll be left stranded.
The bad news is that there is no bypass for a bad fuel pump; you can fix a fuel pump or buy a new one. Another factor could be that your fuel filter picked up enough debris to clog and be unable to permit the proper fuel to exit through the fuel filter.
A fuel filter is a small component within the fuel supply system; its only job is to clean the fuel before it goes into the engine. If the fuel filter is clogged, there won’t be enough fuel to enter the system, and the engine will turn off. The good news is that replacing your fuel filter is an easy task for you to do.
Most fuel pumps are inside the fuel tank. Mechanics have a little secret when a car stops running: give the fuel tank a gentle kick with your foot or similar. If the car starts at that time, you likely have a problem with your fuel pump.
Just don’t hit it with anything sharp, because fuel tanks are plastic and you may breach it, and can I just say that’s the last thing you want to do!
If your car shuts off while driving but immediately restarts, it can be an indication of a bad fuel pump.
3. Empty Fuel Tank.
Most car owners probably know, now and again, when you’re driving, to check your fuel level.
If you have enough fuel for the drive, great! But, if you have no fuel because the fuel gauge or fuel level sender is faulty and you don’t know what the true fuel level is in your vehicle, you have a large problem.
A good way to check if your fuel gauge or fuel level sensor is faulty is to add 1 gallon (4 liters) of fuel to see if it starts.
4. Alternator Problems.
An alternator controls the supply of electricity in your car. If your car just shuts off, the alternator could have just failed. If the alternator in your vehicle is faulty, it will turn off the supply to vital components of the vehicle. You will see your lights in the dash turning off, or your engine will just suddenly lose power.
If your alternator is on the way out, one of the main symptoms you will notice is the red battery light coming on on your dashboard from time to time.
If your car still has electric power to the starter motor after it shuts off while you are driving, you have another problem. Your alternator would not be the issue.
5. Broken Ignition Switch.
In some cases, your car may shut off while driving, and the alternator will be fine. The ignition switch is located behind the ignition lock, and it turns when you turn the key to start the car.
Inside that ignition switch are small metal plates that can corrode and rust. If enough corrosion builds up and one of the plates loses connection, the whole ignition will switch off.
This will also turn the whole engine off immediately. Fortunately, it is easy to check. When your car shuts off, check to see if the lights/ignition lights are still on in your dashboard. If the instrument cluster is dead, you have a high probability that you have a faulty ignition switch.
6. Faulty Sensors.
Modern vehicles now have a multitude of sensors to optimize the air-fuel mixture to achieve optimum fuel consumption. If one sensor fails and is out of specifications, your vehicle’s engine may die altogether.
If you are experiencing your vehicle shutting off while driving but can restart it, or if it shuts down while stopped at idle, or as you are slowing down, this could be caused by a failure of an engine sensor, which could throw off the air-fuel mixture or idle RPM.
Fortunately, the majority of the sensors cannot shut the engine off completely. Sensors such as the MAF sensor, the Coolant temp sensor, or the Oxygen sensors can mess with the air-fuel mixture so wildly that the engine would die.
How To Fix A Car That Shuts Off While Driving?
If your vehicle shuts off while driving, the first thing you need to do to fix it is check the engine control module to see if it logged any error codes and recorded all sensor data. You will also want to ensure the car has fuel in the tank and that the alternator is working properly.
Here’s some more in-depth information on determining how to fix your car shutting off while driving problem:
1. Check trouble codes.
With older car models, to diagnose whether or not the car has a problem, you needed a multimeter or some common sense.
Luckily, with modern vehicles, the car has built-in diagnostics that tell if ‘something’ is wrong. When it detects that one of the engine sensors has an issue, it stores a fault (trouble) code, which is also coupled with a check engine light on the dashboard.
This has made the diagnosing process much easier as you don’t have to waste time checking every sensor in your car engine, and you don’t have to guess and change the wrong parts before you find the issue.
So the best way to determine why your vehicle shuts off while driving is to check your trouble codes from the engine control module, and see if there was anything stored to show there was an issue.
If you want to read the fault codes, you will need to get hold of your own OBD2 scanner or take it to a repair shop that will. Bad spark plugs, the ignition coil, or the ignition system could cause a misfire trouble code.
2. Check the Alternator Voltage.
If you do not have an OBD2 scanner or do not have any trouble codes stored, your next step is to check the alternator voltage with the engine on. You will want to engage the emergency parking brakes and start the engine to measure the voltage of the car battery using a multimeter.
If you have a voltage range below 12.5 volts, there could be an issue with the alternator or the charging system.
Here is an extensive guide on how to test your alternator: How to Test a Car Alternator (5 Steps)
3. Fill the Fuel Tank.
It may seem elementary you should always be sure the fuel tank is filled up; you could also be low on fuel without even knowing it! Low fuel can cause the engine to stall when cornering at high speeds as the pump starts sucking air instead of fuel.
Additionally, there is a possibility that the fuel gauge sensor in your tank is defective, and your fuel level is low even though your fuel gauge is reading full.
So, this is definitely something you want to verify by opening the fuel cap and putting a small amount of fuel in.
4. Check the Fuel Pressure.
Another common cause of your car shutting off while driving is low fuel pressure, and you will want to check the fuel pressure in your vehicle. The easiest and most accurate way to check the fuel pressure is to use a manual pressure gauge connected to your fuel rail or line.
You could also use a diagnostic scanner to measure the pressure if your vehicle has a pressure sensor on it, but there’s always a chance this sensor could be faulty.
Check the fuel pressure specifications for your vehicle, and if you find that the fuel pressure is low, you should check the fuel filter, fuel pump, and fuel pressure regulator.
5. Inspect the Tachometer.
The tachometer or RPM meter on your vehicle is telling you the information from the crankshaft position sensor in most vehicle types.
If your tachometer does not work when your vehicle shuts off, or if the tachometer needle does not move when you turn on the engine, it is likely that the crankshaft position sensor has malfunctioned or the camshaft position sensor has malfunctioned.
6. Check the Dashboard.
When your vehicle shuts off, the next thing to check is the lights on your dashboard. If the dashboard lights shut off when the vehicle shuts off, this might indicate a potential problem with the ignition switch.
This may also indicate low battery voltage, due to a defective alternator, like we discussed in step three. So, if that is the case, you will want to check both of those.
7. Check Sensor Data.
If you can’t find any errors stored in the ECU memory, but you still have an issue with your vehicle, you will want to check all data from the engine sensors by performing an On-Board Diagnostic Test.
To check this data, you’ll want to use a diagnostic tool that is compatible with your vehicle’s Engine Control Module. It can be quite difficult to know what these sensors are supposed to show, so you’ll need to get a repair manual or the specifications for your vehicle first.
8. Visit a Professional.
If you’ve tried everything in the previous sections and your vehicle still shuts off while driving, it may be reasonable to get a professional involved. If it costs a lot of money, and may be reasonable as well to get a professional involved who has most likely been through this situation many times before.
It is not guaranteed that visiting a mechanic will cost more either, if they can find the problem quickly and accurately, rather than replace all the wrong parts.
FAQs.
Can low oil make a car turn off?
Low engine oil levels will not usually cause your car to turn off while driving. But if it is low enough to cause the oil pressure to be low, it may turn off the engine for safety. But typically, this will only happen in newer cars.
Can a bad battery cause a car to turn off while driving?
A bad car battery would not usually cause the engine to turn off since the alternator handles the power required. There may be a short circuit in the car battery, which is rare. This will cause the car to shut down.
Why does my car turn off when I stop?
If your car turns off when you stop, the engine is very sensitive at idle. There can be many different reasons for this occurrence, but most of the time it is due to a lean mixture, and the RPM dropping too low at idle. A faulty throttle body can also be an issue.
Why did my car turn off when driving and won’t start?
If your car turns off when driving and it won’t start, it is likely caused by a bad alternator or low fuel pressure from the fuel pump. Nonetheless, there can be many causes, it needs to be diagnosed using a diagnostic scanner.
When your car shuts off while driving alongside the road, it can be frustrating since sometimes it can be difficult to know what exactly is wrong. Luckily, most modern cars have incredibly precise diagnostic systems that you can use.
So you should always start with the reading of the error codes with the diagnostic tool before you start diagnosing the car even more.
I hope this article has helped you with your car problem. If you have read through this article properly, I am confident you will come up with a solution for your car.