Audi A3 Key Battery Warning: Common Causes and Ways to Fix

Key fobs are the ultimate in convenience when it comes to accessing your car. There's no need to wrestle with your keys, you can simply start your car by pressing a button. But key fobs come with the drawback of a battery that dies after a while. When this battery dies, you could be left stuck out of your car. 

Key battery warning highlights

• Common reasons:low battery in the key fob, keyless entry system problems
• How to fix:change the battery, check the keyless system with the scanner
• Possible consequences:the key fob may stop working at all
• Priority level:Medium
• Can you drive?Yes
• DIY repair:Possible
• Repair price range:$1-$20

In this article, we'll get into the common causes of a key battery warning in an Audi A3, as well as what you can do to fix the issue.

What Is the Key Battery Warning?

A key battery warning is simply your car's way of letting you know that the battery in the key fob is getting low. Key fobs don't come with battery indicators, so they usually catch car owners by surprise when they die. This results in a lot of drivers getting stranded and trapped out of their vehicles. 

The Audi A3 prevents this by bringing up a key battery warning when the key fob battery is getting too low. This heads-up gives the driver ample time to deal with the problem. Dealing with the problem is often as simple as changing the battery. However, sometimes there could be other problems causing the warning, so it's important to know what could be going wrong.

What Can Cause a Key Battery Warning?

If you've been seeing the key battery warning, and you want to get rid of it, you'll need to know what can cause it. The obvious solution is changing the battery. Sometimes this doesn't work though. Let's look at some of the other issues that can cause a key battery warning. 

1) Low Key Fob Battery

Obviously, the most common cause of a key battery warning is a low key fob battery. Usually, the warning will come up sometime before the battery dies, so you'll still have some time to replace it. 

The purpose of the key battery warning is to alert you to the battery status of your A3 key. Sometimes the warning comes up even when the fob battery is fine. When this happens, there's an issue with the car that needs to be addressed. 

2) Software Problem

Your car's computer reads the key fob's battery level. When the battery level falls too low, your car will let you know by displaying the key battery warning. Just like any other electronic device, your car's computer can make mistakes and experience glitches. When this happens, you could end up seeing a key battery warning even when the battery still has some charge left. 

Software problems like this can affect more than your keys. If your car's computer is acting up, you could start to notice false warnings popping up more frequently. 

How to Fix a Key Battery Warning?

You shouldn't make a habit of ignoring your car's warnings. While many of them aren't urgent, like the key battery warning, it will save you a lot of stress if you deal with them as soon as possible. 

Fortunately, dealing with a key battery warning is pretty simple. 

1) Replace the Battery

This solution will fix a key battery warning most of the time. When you're trying to get rid of a key battery warning, the first thing to do is replace the battery. That's because it's the easiest place to start checking, and it's usually the source of the problem.

Replacing the battery is as simple as getting the key fob housing open to access the battery. There are a few different fobs that come with the A3, but all of them typically require you to remove the physical key and press a hidden plastic tab. 

Once you've opened the key fob housing, you can replace the old battery.

Once you've replaced the battery the warning should disappear the next time you start the car. But you might notice some issues instead. For example, you could notice that the key battery warning is still coming up, or the car might not respond to the key at all. 

• Make sure to use the right type of battery. Audi key fobs use CR2032 batteries. These are the little circular batteries commonly found in digital watches. Using anything apart from CR2032 batteries could cause the fob to malfunction or fail.
• Make sure the battery is in correctly. Batteries have a positive end and a negative end. Mixing up these two ends and inserting the battery incorrectly will keep it from powering the key fob. Before inserting the new battery, take note of which side is positive. The positive terminal is marked with a "+". The negative terminal is on the opposite side of the battery. The negative end should be inserted into the key, while the positive end faces outward.
• You might need to wait for the system to clear the error. Sometimes the computer doesn't immediately recognize that the battery has been changed. The warning should disappear after the car has been restarted a few times.
• You might have a bad batch of batteries. This is not an uncommon issue with CR2032 batteries. Sometimes people buy these batteries after they have spent years on the shelf losing their charge. You should get another set of fresh batteries to test with your key fob.

2) Reset the Multi-Media Interface (MMI)

If you've changed the battery, and done everything you can to ensure that the key fob has a good battery, then you might have a software issue with your car's Multi-Media Interface. A simple reset should clear the message. 

The procedure for resetting the Multi-Media Interface in your audio will differ depending on its year. Generally, you'll need to hold down a combination of three buttons on the car's console for about five seconds. After holding down these buttons, the screen should turn black and the system will reboot. You can check the owner's manual of your car to find out the necessary button combination for your vehicle.

Once you've reset the MMI, the message should be gone, along with any other false warnings.

Can You Drive with a Key Battery Warning?

While lots of drivers are comfortable ignoring lights and warnings, many others are more careful about the warnings on their dashboards. If you're more on the cautious side, you could be wondering whether it's safe to drive with a key battery warning. 

Fortunately, you can keep driving safely with a key battery warning on your dash. The warning simply indicates an issue with your key. Your engine and car will continue to run fine, as long as there are no other unrelated problems. 

The major setback from a key battery warning is that your key fob battery could die at any moment. This would leave you with no way to get into your car. Starting your car would also be difficult. 

How To Start Your Car with a Dead Key Fob?

Once you see a key battery warning, you should be prepared for your key fob battery to die sooner or later. Fortunately, there's an easy way to access your Audi A3 

if the fob dies. You can even start your car with a dead fob.

Your key fob contains a physical key that can get you into your car. If you have a newer A3, then you can remove the key by pressing the silver button on the back of the fob and pulling out the silver end. 

In the older Audi A3s, you can flip out your key with a button press.

Now that you're in the car, you'll need to get it started. This is still possible with a dead key fob. You can start your car by placing your fob against the side of the steering column. Specifically, you're looking for a small plastic square on the side of the steering column paneling, around where the ignition would be on a traditional car. 

Once you've held the fob against that spot, start the ignition. Your Audi should roar to life.

Conclusion

The key battery warning is your car's way of letting you know that the battery in your key fob is getting low. It's not the most urgent warning, but you should still try to fix it as soon as you can. Ignoring the problem could leave you with a dead key fob at an inconvenient time. 

Fixing a key battery warning starts by changing out the old battery for a new one. Make sure to put the new battery in correctly. You might need to wait a few key cycles for the warning to disappear. 

If the message remains, then you might need to reset your car's Mutli-Media Interface. This should get rid of the problem, as well as any other false errors.