Car Shuts Off While Driving? (Here’s How To Fix It)

A car that suddenly shuts off in the middle of the road can be very frustrating. Here are the most common reasons why it happens and how to fix it

car shuts off while driving

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 the next time it happens; you are well-prepared.

The most common reason a car shuts off while driving is due to 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 sensors problems.

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 why your car shuts off while driving:

6 Causes of Car Turns Off While Driving

1. Faulty Crankshaft Position Sensor

crankshaft position sensors

The most common reason a car shuts off 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. Here, a faulty crankshaft position sensor may not cause the vehicle to stop entirely.

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 System

cars fuel pump

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

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

alternator

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

igniton switch

Sometimes, a faulty ignition switch can cause your car to shut off while driving. The ignition switch is installed behind the ignition lock and get’s turned while you turn the key to start the car.

Inside of this switch, tiny metal plates can build up corrosion and rust. If this happens, one of these plates may lose connection, and 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

car engine 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.

Luckily, most of these sensors cannot shut off the engine completely, though. Sensors like the MAF sensor, Coolant temp sensor, Oxygen sensor could mess with the air-fuel mixture so much that the engine would die.

How to diagnose a car that shuts off while driving

car diagnostics

Diagnosing a car that shuts off while driving can be difficult if the problem comes occasionally. However, it is much easier to find the problem for a car that just died after driving.

  1. Check for any trouble codes in the engine control unit with an OBD2 scanner. Continue the diagnostics of the trouble code if you get any.
  2. Fill the tank with 1 Gallon or 4 liters of fuel to ensure the fuel level is good, and there is nothing wrong with the fuel level gauge.
  3. Check the battery voltage and connect a car battery charger to make sure the battery charge is good.
  4. If you can start your car after the charging of the car battery. Measure the voltage with a multimeter while the car is running. If it is 13.5-14.5 voltage, your alternator is fine, but if you get under 13 volts while the car is running, there is something wrong with the alternator system.
  5. Check if the engine has correct fuel pressure with a fuel pressure gauge. If not – check the fuel pump and fuel filter. Replace if faulty.
  6. Check live data with your diagnostic tool and look for any strange values from the engine sensors. Check if you get RPM from the crankshaft sensor when cranking the engine.
  7. Check the RPM meter on your dashboard while cranking the engine on the starter motor. If it doesn’t move – the problem is most likely the crankshaft position sensor.

Can low oil cause a car to shut off?

Low engine oil levels do usually not cause your car to shut off. However, if it is so low that your oil pressure is getting low – the car can shut off the engine for safety reasons. This is often in newer cars, though.

Can a bad battery cause a car to shut off while driving?

A bad car battery rarely causes the engine to shut off because the alternator gives the required power it needs. It can be such a short circuit in the car battery in some rare cases, so it will shut off, 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 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 shut 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.



Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.