Why My Car Shuts Off While Driving? | Why Car Turns Off While Driving?

It is very frustrating when your car suddenly shuts off while driving. This condition is very dangerous, particularly when driving on a busy road.

If you have a car, you must properly maintain it. Maximum car owners seem to believe that their cars are powered by magical dust. To ensure your car engine runs efficiently over a long period of time, you must have sufficient coolant, gasoline, oil, etc.

Car Shuts Off While Driving

The latest car models contain multiple sensors and functions that ensure the smooth running of your car. Knowing the basics of your car can help you troubleshoot mechanical problems, such as: if your car suddenly stops while driving.

This article mainly explains why your car turns off while driving and how to fix it.

Causes of Car Shuts Off While Driving

A bad fuel system or a bad crankshaft position sensor is one of the major reasons why your car shuts off while driving. Your car turns off while driving due to insufficient engine oil, a broken timing belt, bad engine sensors, a bad fuel system, insufficient fuel, a bad alternator, a dead battery, faulty engine sensors, engine overheating, an ignition switch, or a faulty radiator.

The below-given list explains the causes why your car shuts off while driving:

1) Faulty Crankshaft Position Sensor

A bad crankshaft position (CKP) sensor is one of the major causes a car shuts off while driving. The crankshaft position sensor plays a big role in ensuring the efficient working of the engine.

Crankshaft Position Sensor, Causes of Car Shuts Off While Driving

The main function of the crankshaft position sensor is to measure the position or rotational speed of the crankshaft and sends this information to the powertrain control module (PCM). The PCM uses this information to control the fuel injection rate, the ignition system timing, and other engine parameters.

As the CKP sensor goes bad, it doesn’t send the correct information to the PCM, and you may face different issues in your vehicle such as poor engine performance and poor fuel economy. However, a bad crankshaft position sensor may not cause the vehicle to stop entirely, though.

Read More: Bad Crankshaft Position Sensor Symptoms

2) Bad Powertrain Control Module

The car may also die while driving due to a bad powertrain control module (PCM).

Function of PCM

The main function of the PCM is to collect data from different parts and sensors of your vehicle engine and uses this data to produce the desired power and efficiency of the vehicle by controlling the engine’s spark and fuel. It works efficiently when there is a proper flow of information from the PCM to the sensors and the sensors to the PCM.

For instance, the PCM coolant sensor measures the engine temperature, and if faulty, it will shut down the engine to avoid overheating, thus saving the car from further damage.

If the PCM gets wrong information from any of the faulty sensors, your car may experience shutting off while driving.

Read More: PCM Function, Symptoms, and Causes

3) Insufficient Fuel

You should always check your fuel in the fuel tank before driving. Insufficient fuel is one of the most common reasons a car dies while driving.

Insufficient Fuel which causes a car turns off while driving

Your vehicle engine contains a fuel sensor that measures the fuel level in the fuel tank and sends this information to the PCM. The PCM shows fuel sensor information on your vehicle dashboard.

When the fuel gauge warning light starts illuminating on your vehicle dashboard, it means that your vehicle fuel tank doesn’t have sufficient fuel.

If you have adequate fuel for your car engine, 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.

4) Ignition System Issues

The ignition system has the responsibility to generate a spark that burns the fuel-air mixture in the combustion chamber. The burning process of the air-fuel mixture generates the power required to run the car. The car engine can’t generate power without a spark from the ignition system.

Ignition System

As you can imagine, a problem with the ignition system can lead the car to stall while driving. This problem usually generates due to a bad part in the ignition system that affects the combustion process of all the engine cylinders (e.g., a bad CKP sensor) and not by a part that disturbs only one cylinder, such as a bad spark plug.

The bad ignition switch may also lead to engine stalling. As you turn on your car key in the “run” position, the ignition switch offers a path for power to flow from the battery to engine management parts such as ignition coils and fuel injectors. As this switch goes bad, it doesn’t generate a path for the power to flow and your engine stalls.

5) Internal Engine Failure

The most serious scenario is definitely the car dying from an inner engine failure. If the engine fails, you will most likely hear annoying noises such as knocking or rattling noise before the car shuts off. In maximum scenarios, a vehicle engine that dies from an internal engine failure can’t be restarted.

6) Battery Problems

A dead battery is one of the major causes of a car turning off while driving. Your car’s charging system and battery are responsible for supplying power to all of the electrical parts in the car, along with the parts that ensure the engine runs (such as PCM, injectors, etc.).

The problems such as a loose battery cable can drain power from the entire vehicle and stop the engine from running.

car Battery

7) Clogged Fuel Injectors

The clogged fuel injector is one of the most common reasons a car turns off while driving. The most expected cause is a dirty injector. Fuel-injected vehicles need fuel injectors to deliver the right amount of fuel at a precise time.

Leaky Fuel Injector

Even a drop of dirty gasoline in the injectors can clog all the holes and lead your vehicle to die. The most common side effect of a clogged injector is that the vehicle will start, run for a few minutes, and then shut off.

8) Bad Sensors

The engine consists of multiple parts and sensors. Whenever any of these sensors go bad, your powertrain control module (PCM) triggers a code.

MAF Sensor, mass air flow sensor

Luckily, most of these sensors can’t turn off the car engine completely. Sensors like the Oxygen sensor, knock sensor, MAP sensor, Coolant temperature sensor, and MAF sensor may disorder the fuel-air mixture so much that the engine would die.

9) Alternator Issues

The alternator distributes the power supply throughout the vehicle. A bad alternator may suddenly shut off your car while driving. A bad alternator can cut the power supply to critical parts of the vehicle, and you may find your dashboard lights go out or your engine suddenly loses power.

Alternator

Overloading or overcharging the alternator may also cause the car to stall while driving.

Occasionally a red battery light will appear on the vehicle dashboard, mainly when the alternator has failed.

If your vehicle still has power and the starter engages while driving after you turn it off, then you may have another issue instead of the alternator.

10) Faulty Throttle Body

Throttle body damage is a leading cause of engine stalling. This is the part of the engine responsible for delivering the precise amount of air and fuel to the combustion chamber and controlling the power produced by the engine.

bad Throttle Body

The throttle body is located between the engine and the accelerator pedal. As you press your gas pedal, a signal is sent to the throttle body. The throttle body then opens, allowing more air and fuel to go into the combustion process, increasing engine power.

11) Faulty Fuel System

The efficient working of the fuel system is very important for the efficient working of the vehicle. A fuel system consists of a fuel pump, fuel filter, fuel injector, carburetor, fuel rails, and fuel pressure regulator. Whenever one of these components goes bad, your car will not run properly; even it may turn off completely.

fuel injection system working

A fuel pump is used to supply fuel from a fuel tank to the carburetor of an internal combustion engine.

If your fuel pump doesn’t supply fuel to the engine, it will shut off, and your vehicle will be stopped. Therefore, as your fuel pump goes bad, you should replace or fix it immediately.

A fuel filter is part of the engine that eliminates dust and dirt particles from the fuel. If the fuel filter is clogged, the fuel entering the system will be insufficient, and the engine will shut down.

Read More: How does Fuel System Work?

How to fix a Car that shuts off While Driving

The following repairs or fixes may help you to fix a car that shuts off while driving:

  1. Check trouble codes
  2. Check alternator voltage
  3. Fill the fuel tank
  4. Check fuel pressure
  5. Check the tachometer
  6. Check the dashboard
  7. Check sensor data

1) Check Trouble Codes

For old models of cars, you may need to use a multimeter or common sense to find and fix the car problem. Luckily, the latest cars have onboard diagnostic software that can detect an issue with one of the engine’s sensors and store a trouble code.

The latest vehicles contain a powertrain control module (PCM). It is connected to multiple engine sensors. Whenever any of these sensors go bad, it sets a specific code. 

This makes diagnosis easier and saves you the time of measuring every sensor on your car’s engine. Plus, you don’t have to guess and replace the wrong part.

The best method to tell why your car shuts off while driving is to check the PCM for these trouble codes to check if there is any saved problem.

However, an OBD-II scanner is required to read the trouble codes. Buy it yourself or go to a repair shop that will read the code.

Continue troubleshooting using the data you got from the OBD-II scanner. For example, if you find a fault code for the camshaft position sensor, you should inspect the wirings for that sensor and possibly replace the sensor. 

2) Check Fuel Pressure

Low fuel pressure may cause the car to turn off while driving. Therefore, you must continuously inspect your car’s fuel pressure. One of the ideal methods to inspect your fuel pressure is to connect a manual pressure gauge to your fuel line or fuel rail.

A diagnostic scanner can also be used to check the pressure from the fuel pressure sensor (if equipped), but there is always a possibility of damaging that sensor.

You must regularly check your car’s fuel pressure. If the fuel pressure is too low, you should inspect your car’s fuel pressure regulator, fuel pump, and fuel filter.

3) Check the Dashboard

Inspect the car dashboard lights when the car turns off. If you observe the dashboard lights going off when the engine is off, this could show an issue with your ignition switch.

4) Check Alternator Voltage

As we discussed above, the alternator is one of the major reasons a car shuts down while driving. To check the alternator, examine the alternator voltage while the engine is operating.

For this, just start your engine and use a multimeter to check the voltage of your car battery. If the reading is less than 12.5V, the alternator may have an issue.

5) Check the Tachometer

The tachometer is commonly installed in most cars. It is located on the car dashboard. It gets input from the crankshaft position sensor.

If the tachometer doesn’t work when your car shuts off while driving, or if the tachometer does not work when you start the engine, you may have a problem with your CKP sensor or CMP sensor.

6) Fill the Fuel Tank

Low fuel can cause the engine to stall when cornering at higher speeds because the fuel pump will suck air instead of fuel.

You should always check your fuel level before driving. If fuel is less than the desired level, then add more fuel.

Read More: How to Change Engine Oil?

7) Check Sensor Data

If you cannot find the trouble codes stored in the PCM but you are still having problems with your vehicle, you should examine the data of the engine sensors.

To check this data, use a good-suited diagnostic tool for your PCM. It’s also hard to know what those sensors are reading, so you’ll need to get hold of a repair manual or vehicle specs first.

FAQ Section

Can low oil cause a car to shut off?

A low engine oil level doesn’t generally lead the car engine to shut off while driving. However, the car may stop the engine for safety if the oil pressure is too low. However, this usually only occurs in new vehicles.

Why does my car turn off while driving and then start again?

Sometimes the car can turn off but then restart if there are issues such as a bad alternator or a battery, engine overheating, bad fuel injector, damaged timing belt, fuel system problem, or low fuel level.

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

Yes, a bad battery in your car may cause the car engine to shut off because the alternator transfers the power from the battery to the car’s electrical parts.

When your car battery goes bad, the car electrical components such as spark plug, fuel injectors, and fuel pump don’t receive power and stop working, which causes your car to shut down.

Why does the car shut off while driving with no check engine light?

If the car randomly shuts down like this, it is most likely due to a faulty crankshaft position sensor. This is a common issue, and it will not lead the check engine light to not illuminate.

How to avoid a car that turns off while driving?

  1. If your car is having trouble starting up, it may indicate that there’s a problem with either the fuel pump or the fuel filter. In such a situation, replace or repair your fuel pump or fuel filter.
  2. Replace the broken, worn-out, or faulty spark plugs.
  3. Check the ignition coil and distributor cap, as they may be faulty. Worn out, broken, or improperly installed ignition wires can also lead to engine misfires.
  4. A faulty or defective fuel pump relay may cause the car to stall while driving in lower gears.
  5. Replace or repair the damaged fuel cap
  6. Replace or repair the faulty the crankshaft position sensor
  7. Replace or clean the faulty or clogged fuel injector
  8. Replace the faulty sensors
  9. Fix the battery-related issues
  10. Replace or repair the bad alternator
  11. Properly check your fuel level before driving. If fuel is less than a specific level, then add more fuel.
  12.  Replace or repair the faulty radiator
  13. Fix the engine overheating issues

Why does my car randomly cut off while driving?

There are many causes why the car engine suddenly shuts down. These include engine overheating, an empty fuel tank, a bad camshaft sensor, a defective crankshaft sensor, a dead battery, or a defective alternator. As you face this issue, it’s important to drive your car to the nearest workshop.

Why my car turns off while driving but turns back on?

Your car turns off while driving but turns back on due to a bad crankshaft sensor, bad camshaft position sensor, insufficient engine oil, insufficient coolant, a bad alternator, bad battery, a problem with the fuel system, a broken timing belt, faulty engine sensors, engine overheating, faulty ignition switch, or faulty radiator.

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