Why Your Car shuts Off While Driving But Restarts

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If your car shuts off while driving, this can be one of the scariest moments. Not only is it scary, but it’s also dangerous. Unfortunately, countless reasons can cause your car to turn off.

Don’t stress out or panic. You should first get your car to a safe place off the road and avoid driving it until you know it’s safe.

I’m here to help you diagnose why your car is turning off but still restarting when driving. In this post, I will go over some of the most common reasons that can cause your car to shut off as your drive and a few things you can do to try and fix it.

Let’s get started.

6 Reasons Why Your Car Can Shut Off While Driving but Still Starts

1. You Ran Out Of Gas

Running out of gas is one of the most common reasons a car can turn off while driving.

While this seems like a basic and trivial reason that your car has turned off, it happens more than often.

In many cases, it’s easy to forget to refill your gas due to busy life or malfunctioning gas gauge or dashboard.

The first thing you want to do is check your gas gauge and make sure that it’s above the “E”. If your gas gauge is near or below the “E”, this is likely the issue.

Even if your gas gauge is not on “E,” but your gas gauge has not moved in some time or is stuck in a single position, you can still be out of gas.

If this is the case, you likely have an issue with your gas gauge. This causes the gas gauge not to read your gas levels properly.

Make sure you always pay attention to your gas gauge before and after you add gas. If there is no movement after you add gas or after you’ve driven at least 20 miles, you should have your gas system checked out by a professional.

You might be wondering why your car is still starting even if you are empty. This is because there could be minor amounts of fuel within the fuel system that is enough to start your car.

Even if your car does start, it’s likely that it won’t run for long, so you are not out of the woods yet. I recommend you add some gas using a tank or immediately add gas to your car. It’s likely you only have about 1-3 miles of driving distance, so find a gas station nearby.

2. Damaged or Faulty Alternator

The alternator is much more important than most people realize. It is your car’s alternator is your car’s powerhouse.

While the battery is vital to starting your car, your alternator will recharge your battery and continue providing electricity to your battery.

If your alternator is faulty, your car may eventually run out of battery. Over time this can cause your car to turn off.

With a faulty or damaged alternator, your battery might be able to recharge enough to restart and drive short distances. It’s likely that as you continue driving or starting your car more times it will eventually turn off again.

If your car turns off, you should check your battery. If there is an issue with your battery, then you should also check your alternator. These two issues are likely connected, especially if your battery is new or there are no connection issues.

3. Damaged or Faulty Fuel System

A faulty or broken fuel system is another common reason your car might shut off while driving and restart—the fuel system stores and supplies fuel to the engine. 

With a damaged or faulty fuel system, your engine will not receive the necessary fuel it needs to run properly. As a result, your engine will turn off. 

With a faulty fuel system, the results are very similar to running out of gas. The problem is that it’s hard to determine when your fuel system is not working properly with a faulty fuel system. 

In some cases, your fuel system may function perfectly when starting but may have issues injecting more fuel into the engine as your drive. 

As a result, even if your car continues to turn off as your drive, you may still be able to restart your car. 

Some common issues with the fuel system include issues with the 

  • Fuel pump 
  • Fuel filter 
  • Fuel supply line 

The best way to diagnose fuel system issues is to take it to a professional. Not only can they identify the issue, but they can also begin repairing your car.  

4. Faulty Engine Control Unit (ECU)

The Engine Control Unit or ECU controls a series of mechanisms inside the engine for optimal engine performance.

The ECU is crucial to your car’s operations; without a functioning ECU, your car won’t run properly.

If you have a faulty ECU, you may drive for a short period, but your car is undrivable once it fails.
One of the common symptoms of a faulty ECU is your car stalling and jerking while driving. It’s also possible that your car will shut off randomly and turn back on.

This is because the ECU can cause sudden drops in power, fuel efficiency, and spark loss. These can cause your car to turn off and turn back on when the ECU is malfunctioning.

Unfortunately, testing and inspecting your ECU is not easy. The easiest way to determine you have a faulty ECU is with an OBD scanner. But DTC codes are not clear cut for a failing ECU. This makes diagnosing a faulty ECU difficult.

The best way to determine if you have a faulty ECU is to take your car to a mechanic. A mechanic will have the right tools, software, and understanding to diagnose your ECU.

5. Faulty Spark Plugs

Your spark plugs are not only important to start your vehicle but they also make sure that the fuel and air mixture is optimal as you drive. If your spark plugs stop working as your drive, this can cause your car to turn off or stall out. 

The confusing part is that it’s very likely that if you continue trying to restart your car, it will likely restart. This doesn’t mean you don’t have issues. Your car will likely continue to turn off. 

If you suspect an issue with your spark plug, you should address them immediately. Issues with spark plugs can cause other spark plugs to become damaged. In addition, it can also lead to other major issues inside your engine. 

If multiple spark plugs are faulty, your car may start, but it most likely won’t drive long. The imbalance can cause your engine to stall and turn off.

Typically there will be several vital signs before your car reaches this stage: misfires, reduced engine performance, lack of acceleration, engine knock, among others.

You can read our in-depth article here for more detailed information on the key signs of bad spark plugs.

An easy way to determine if you have a bad spark plug is to inspect them. This can be easier or harder to do, depending on your car.

Once you can physically see your spark plugs, the condition of your spark plugs will be evident. Below is a guide you can use to track the condition of your spark plugs.

 

spark plugs condition chart

Resource: 6 Symptoms of Bad Spark Plugs

6. Dead or Faulty Battery

A faulty or dead battery is another common reason that your vehicle might turn off when you are driving.

This can either be due to a faulty or old battery that is not holding a charge. As your battery dies, your car will eventually turn off if you continue driving on a dead battery.

Another potential reason that your car may shut off is if your battery terminals or cables are faulty. Even if your battery is in perfect condition, bad battery cables or terminals won’t allow your battery to transfer electricity to the rest of your vehicle.

In this case, you will likely be able to restart your car. If you wiggle your battery cables or they move as your drive, you might be able to start your car.

Also, it’s possible that your battery might have just enough charge to start your vehicle.

Diagnosing a faulty battery or issues with your cables is typically easy. You can use a battery tester or voltage meter to check your battery and your battery cables.

If you are not getting the ideal reading, you should then identify where the problem is.

The easiest way to check your car battery is using a multimeter. Your car should have a voltage of around 12.6 volts.

If your battery is showing anything less than 12.6v, then your battery is not fully charged.

If your battery is below 11.7v, you need a new battery. At 11.7v, your battery is holding less than 25% of its charge.

What To Do If you Car Dies While Driving?

Below are the steps you should follow if your car dies while you are driving. 

  1. Don’t panic. Stay calm and turn your emergency lights on. 
  2. Begin to guide your vehicle to the side of the road. Don’t stop immediately or stop in the middle of the road. 
  3. Move as far to the side of the road as your can.
  4. Try to restart your car. Only try two to three times to avoid causing more damage. 
  5. Remember, if your car does not start and you’re on a major street or highway, don’t get out of your car. If you really need to get out of your vehicle, you should try to exit the passenger side. Always stay away from your car when you are waiting outside your vehicle. 
  6. If your car does start, you should only drive your car off the road or to a safe place nearby, such as a parking lot or road with less traffic. 
  7. Once you are in your final position, whether at a parking lot or pulled over on the shoulder of the road, you should call for help. 
  8. The best place to call for help is a tow truck or AAA to either help restart your car or two your vehicle to a professional to have it diagnosed. 

It’s important that you don’t continue driving your car like anything happened if it does restart. If you continue driving, this will likely make the issues worse and cause more issues to arise.

You should always have your car inspected by a mechanic to help you determine the issues. Catching these issues early will save you money and more damage to your car. 

Conclusion

There you have it. Here are seven of the most common reasons that can cause your car to turn off while you drive but still restart. 

If you car does turn-off and then turn back on, run through this list and try to eliminate each reason. 

The easiest way to determine if what the issues is to take your car to a professional. Remember it’s important to take action and not put off the issue. Putting off the issue will only result in more damage and dangerous driving condition. 

Don’t wait any longer and take action today by inspecting your car and identifying the issue. 

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