Why BMW Won’t Start After Changing the Dead Battery?(Fixed)

One trouble we always went through with our BMW was the car not starting up. Particularly, this happened when we replaced a dead battery. If you are struggling with the same thing, then we will tell you why BMW won’t start after changing a dead battery.

A very obvious reason for that is an incorrect battery installation. Aside from that, a faulty battery, blown fuses, issues with the battery safety terminal, or starter component can cause it. Not reprogramming the BMW computer is another prime reason.

Now, if you are still wondering why, you might have this trouble, we recommend going through the whole article. We will discuss the causes in detail as well as their fixes. Let’s get going then.

Why won’t BMW Start After Replacing the Dead Battery?

Before you check out these causes, one thing you should focus on is that you have changed the dead battery. These things only matter if you have changed the battery of your car recently.

Considering you have done that, let’s check out the causes and fixes when your BMW isn’t starting after you replace the battery.

Incorrect battery installation

One of the most common and easiest to fix issues that causes this problem is not installing the battery properly. Whenever you don’t install the battery properly, it will not function as a result you can’t even start up your car.

To fix the problem, you don’t have to do much. You just have to make sure that you are installing the battery following proper procedures. Don’t worry, we will be discussing the battery replacement process later on in this article.

Faulty battery

Another concern that’s related to the battery is a faulty battery. It’s pretty logical that your car won’t start if the battery has some faults in it. The battery we are talking about here is the new battery that you will be replacing the dead battery with.

Fixing the problem isn’t that difficult. All you have to do is test the battery with a multimeter and see if it’s okay or not. If the battery isn’t in good condition or has flaws in it then you have to replace this battery as well.

Our suggestion to avoid this problem is simple, try checking the battery beforehand. Usually, you won’t have any trouble if you have gotten a new battery from a renowned brand. Still, it’s better to check the battery before installation.

Blown out fuses

If your battery and battery installation is good, then the next thing to check is a blown-out starter fuse. A blown-out fuse will cause difficulties in starting the car. You can have the same issues with starting your BMW if the ECM fuse is also blown out.

Solving the problem doesn’t require much. You can get replacement fuses from the internet or from local mechanic stores. Then, locate the fuse box and it can be in different places. Try referring to the BMW manual you got with your car and you should find the fuse box.

Problems with the battery safety terminal

Battery safety terminal is a special feature on BMW cars that you get. It usually disconnects the battery if it can detect an accident. Whenever the battery safety terminal connection has a faulty connection, it will prevent the car from starting.

First thing you have to do is find the battery safety terminal. Then, check if the feature is activated or not. If it’s not activated then you have to check up on the battery safety terminal connection. You can try establishing the connection yourself.

A good way to determine whether this is the problem or not is to check if the lights and radio are coming on or not. If they are coming on and your car isn’t starting then it’s probably the battery safety terminal.

Issues with BMW starter component

Most of the times the BMW starter component going bad can result in the car not starting. It’s not something that only happens after changing a car battery, still, it’s a possibility for your BMW not starting.

Typically, your engine not turning over or noises and smoke coming from the starter is a clear indication of this problem. So, when the starter component is causing the issue, you will clearly know about it.

Solution to this problem is simple: you replace the starter component. However, the difficult part is to replace it by yourself. That’s why, we highly recommend going to a mechanic to replace the starter component of your car.

Issues with the BMW computer

When it comes to starting your BMW, the computer can also be responsible. Every time after changing the battery of your BMW, you have to reprogram the computer to make it work. Otherwise, your car won’t start because the battery isn’t connected properly.

While the BMW computer can read the battery specifications itself and reprogram accordingly, it may fail to do that sometimes. That’s when you have reset the BMW computer to connect the battery properly.

Not resetting the computer can lead to the car battery not charging as well. So, it’s important for you to reset the computer on your BMW. Don’t worry we will discuss that later on in this article.

How to replace a dead BMW battery without any issue?

Among all the different issues the most common one is incorrect installation of the battery. It’s just something you must know, so you can avoid this situation of BMW not starting after you change the battery.

Here’s how you can replace the dead battery on a BMW –

Step-1: Getting the right kind of battery

First you have to get the right kind of BMW battery based on the model you drive. Once you have that, you can go ahead with the next steps.

Step-2: Taking off the different covers 

Start the battery removal process with taking off the liner cover of the battery. Before doing so, make sure the ignition is off and also the key isn’t inserted in your car.

Step-3: Remove the battery terminals 

Once the cover is off, you can start removing the battery terminals. First remove the negative one then the positive one.

Step-4: Remove the brackets and battery 

After that, removing the brackets is a necessity. To do that, you just take off the bolts on the brackets. When the brackets are off, the BMW battery should be free to remove.

Then, you can start removing the battery from the trunk. You shouldn’t have too much trouble but be wary that the battery might be heavy. 

Step-5: Installing the new battery 

Before installing or putting in your new battery, make sure to note the battery information. It’s important for registering the new battery.

Next, you place the new battery in the trunk. Ensure that the battery fits the space properly.

Here’s a crucial step you must be careful with. You have to secure the battery properly using the brackets. When you are tightening the brackets, make sure not to overdo it.

Step-6: Finishing off the installation

Afterwards, you should clean up the battery posts where the battery terminals are supposed to go.

Then, connect the battery terminals. First do the positive one and then do the negative one. Finally, put back the liner cover on the battery and cover everything up.

That’s pretty much what you have to do to install a new battery flawlessly. But wait a minute, the process isn’t complete. If you have a BMW car that has a computer in it, then you will need to register your battery and reprogram your computer. Let’s check that out.

How To reset a BMW computer after replacing the dead battery?

Resetting the BMW computer is a very crucial factor for anytime you replace a battery on a BMW. It’s something that you need to do for registering the battery and charging the battery properly. It also helps out with other functions.

Now, let’s get to the part of how you can reset the BMW computer very easily. Here are the steps –

Step-1: Getting your BMW to accessory mode

The first thing you have to do is get your car into the accessory position. Usually, turning the ignition to accessory mode does that on your BMW. It’s where your car won’t start but the radio and lights will turn on.

Step-2: Reset the BMW computer 

Next, you have to keep holding the “Trip” button you have on the panel. You have to hold it until you see the red light.

Afterwards, leave the button and press it once again. This time don’t hold it and you should see the “Reset” message appearing on the screen.

Finally, for the last time, you have to press the button again and you will have reset the BMW computer.


It’s not over yet, we have something more to offer you. Here, we will be discussing some common questions related to BMW battery replacement and its issues. These ones may be quite helpful for you.

How do you start a BMW with a dead battery?

You can try out different methods to start a BMW with a dead battery. One method is to recharge the battery and start it. Another method is to jump the battery. Pressing the FOB against the steering column in a particular location also starts the car.

How long do you have to drive a BMW to charge the battery?

This answer mostly depends on the model of your car. But in general, it can take around 20 to 40 minutes for your BMW to charge the battery enough to run it. You have to cover a distance of around 30 miles.

Does idling a BMW hurt the battery?

Yes, idling your BMW car can hurt the battery. Because when you put the BMW in idle mode, it starts draining the battery. BMW in idle will never let it charge fully. It’s better to drive the car than putting it on idle.

How long can a BMW battery be dead and still be recharged?

While this mostly depends on the make and model of your car, it can keep it for about 1 to 2 months. But it’s better to charge the BMW battery every once in a while, if you can.

What happens if you don’t reprogram your BMW computer?  

If you don’t reprogram the BMW computer of your car, then it doesn’t register the battery. Without registering the battery, you will have trouble charging it as well as using it properly. Your car may not even start at times.


There you go, now you know why BMW won’t start after changing a dead battery. These causes are very easy to figure out as they are pretty evident. Most of the time, it’s related to the battery or the BMW computer.

However, what we recommend is to troubleshoot your car. It’s important to troubleshoot your car to determine which of the reasons are causing the problem. Start from the easy ones related to the battery, then move on to the complex ones.

When you have that down, you won’t have to bother too much about this issue. Fixing the problems for the most part requires you to replace some parts or they are very easy fixes that you can do yourself.

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