Car Stalling After Battery Change [Why + How To Fix]

From many years of experience repairing cars, I can tell you that the number one reason behind a car stalling after battery change is when it loses the idle settings.

The electrical system in modern cars is highly advanced. But even if you turn them on for a second, they can lose the settings and cause this stalling issue.

Don’t worry, all hope is not lost if your car stalls after a battery change. I’ll show you how you can reset the idle settings and how you can retain the settings during your next battery replacement. So, let’s dive in!

What Causes Car Stalling After Battery Change?

Replacing the car battery when it goes bad is normal for every car owner. But sometimes, doing that can bring on additional problems. In this case, you may face the issue that your car engine is stalling.

Firstly, it’s crucial that you realize that you haven’t done anything wrong. When a battery goes bad, replacing it is the right thing to do. So then, why does the engine stall after you’ve changed the car battery?

The main reason behind it is that cars have kind of evolved into moving computers. What I mean is that, unlike older cars, modern cars are controlled by a central computer. It’s called the ECU or ECM.

There are many settings stored in the ECU of a car. As you keep driving your car, the ECU keeps learning about your driving pattern and stores those settings. These settings are stored and saved in a part of the computer called the VRAM.

You always have to keep a power supply connected to the computer so that it remembers the settings. If the power was to be disconnected, even for a second, the computer would forget the settings. And that’s precisely what happens when you replace the car battery.

Several VRAM settings including the idle settings can get lost when the power supply to your car is disconnected. That’s the most likely reason why a car stalls after replacing the battery in it.

When your computer loses its previous settings, it’ll go back to its default settings. The default settings are good for new vehicles. But they’re not set according to your driving behavior. With time, you’ll have to retrain the computer of the car to solve this issue.

How To Reset Idle After Replacing Battery?

Losing the idle settings stored in the VRAM is the number one culprit of why your car stalls after a battery change. But you don’t have to worry about it too much as it’s an issue that’s relatively easy to fix. Your car can relearn the settings if you follow the instructions correctly.

Firstly, the throttle body could be dirty and it could be partially blocked. There’s also the possibility that it could be sticking open. So, clean the throttle plates and the idle control valve so that the idle settings can match up.

Once you do that, it’s time to start making the computer relearn the idle settings. You can follow these steps to do it:

1. Park the vehicle on level ground and make sure the parking brake is set. Wait for the engine to cool down. Then, turn off all the electrical components including the interior lights, AC, and the audio system.
2. Start the engine and give it some gas if it feels like the car is about to stall. Look closely at the temperature gauge and wait for the car to get completely heated up.
3. If the vehicle is idling smoothly by itself, turn on the AC and see if that’s still the case. Doing that will tell you if the ECU is adjusting to the additional load due to the AC being turned on.
4. If the vehicle is not idling properly, drive your vehicle on an open road for 20-30 minutes. Avoid driving the vehicle in a congested area as you’ll have to use both feet.

Hopefully, that’ll help your computer relearn the idle settings. However, there’s another approach you can take to do the same job. You can choose which method you want to follow. Here’s another method that’ll also help your computer adjust to the old idle settings soon:

1. Start the engine and let it run around 1500 RPMs for a few minutes to warm the engine.
2. Then, let the car idle and turn off the electrical accessories for a few minutes.
3. Next, put your car in drive and turn on the AC at medium speed. Let the car idle in gear for a couple of minutes.
4. Then, put the car back in park and let it idle for the same duration with the AC turned on. Then, drive your vehicle for 6-8 miles and road test it.

Hopefully, that’ll fix any idling issues in your car and your engine won’t stall anymore. If your car still stalls even after you follow the above steps, there could be a bigger issue with your car.

There could be several reasons other than a battery change that can cause your car to stall. Electrical problems, low fuel pressure, or a faulty alternator could also lead to this problem.

Check out our guide on bad batteries making cars stall to learn more about these problems and their fixes. If you still can’t fix your car, then you should take it to a mechanic until you identify the root cause behind the issue.

How Can You Prevent The Car From Stalling After Battery Change?

You may have heard the age-old saying that prevention is better than cure. By now, you should know that the car stalls because it forgets the idle settings. That only happens because the power supply gets disconnected.

But it’s better to prevent that issue altogether. And you can do that with the help of a device called a memory saver. If the memory saver is plugged into a source, it’ll maintain the power supply to the computer.

So, the settings stored in your VRAM will be retained that way. Your idle settings won’t be changed and your car will no longer stall.

Keep in mind that the idle settings aren’t the only thing that could get lost when the power supply gets disconnected. In fact, things like the overall computer memory, radio settings, clock, and other things can also be lost when you replace the battery.

Luckily, a memory saver will protect all these settings and keep your car as it was even after the battery replacement. There are many ways in which you can connect the memory saver to your car.

The main source is the OBDII diagnostic port under the dashboard in your car. The power supply of these memory savers can also be different. Some are powered by 9-volt batteries while others use rechargeable batteries. There are also memory savers that can be connected to a power outlet.

It’s not just me. Clore Automotive says “One way to prevent these problems during a battery change is to utilize a memory saver to keep the vehicle powered throughout the swap”. So, you should really take the help of a device like a memory saver when changing your car battery.

How To Use A Memory Saver To Protect The Settings In Your Car?

You need to get the right type of memory saver for your car. Check if the cigarette lighter or power port has power after you turn off your car. If there is power, using a memory saver with a lighter plug adaptor will be enough.

But if there’s no power, you’ll have to use a memory saver that can be connected to the OBDII port. With that said, here’s how you can use the memory saver the next time you change the battery in your vehicle:

1. Turn off your car and connect the memory saver to the designated port.
2. Remove the old battery and replace it with the new battery like you normally would.
3. Make sure that the battery connections are tight, clean the battery terminals to avoid corrosion, and secure the battery in place.
4. Disconnect the memory saver before you start your car.

That’s how easy it is to use the memory saver. Hopefully, doing so will not only maintain but the improve the idle settings in your car. That’s because your old battery was most likely performing poorly and the new one will run smoothly. 

What Battery Installation Mistakes Can Lead To The Car Stalling?

I’ve explained the stalling issue so far with the assumption that you replaced the battery correctly. But there are actually several installation mistakes you could have made that could lead to this issue. Here are the issues you should be on the lookout for when replacing the car battery:

Keeping The Battery Connections Loose

If the battery connections are tight, the proper flow of electric current will be interrupted. It can also cause stalling and issues starting your car. Inspect the battery connections and make sure they’re tight.

Using The Wrong Type Of Battery

The battery you’re using needs to be the right type for your vehicle. If you use a smaller battery than what your car requires, it can lead to power and voltage issues. So, your car could be stalling at times. Consult the owner’s manual of your car and make sure the battery you’re using is of the right size and type.

Not Cleaning Corroded Battery Terminals

Even though you’ve installed a new battery, it won’t make a good connection if the terminals are corroded. So, make sure that they’re clean. If they’re dirty, you can clean them by spraying some WD40 and using a battery terminal cleaner. Once you do that, hopefully, the stalling issue will go away.

So, those were the most common mistakes that you could have made when replacing the car battery. Make sure you avoid them and do a good job the next time you replace the battery in your vehicle. If you do that, you won’t have to worry about the engine stalling at all.

FAQs:

Conclusion

Why is my car stalling after a battery change? You don’t have to wonder about it as you know why it happens after reading this guide. All you’ll have to do is reset the idle settings. You can also use a memory saver to prevent this issue in the first place.

The memory saver will retain the settings and you’ll have no issues after replacing the battery. I also have a guide on what you should do if the car shuts off due to the battery getting disconnected. Check it out if you face this issue and need to solve it.