How To Change The Battery In An Audi Key Fob

The modern key fob is a clever and convenient way to unlock and lock your car, and in many instances, key fobs do far more than just this. This is all well and good, but what happens when pressing the button fails to get a response from your car? In most cases, the problem is easily remedied by replacing the battery. The good news is that most key fob batteries will last for years. Exactly how long is hard to quantify as factors like climate, usage, and the type of battery all have a bearing on it. Audi key fobs are no different, and sooner or later the time will come when your battery needs to be replaced.

Ideally, you'd want to change the battery in your Audi key fob before it fails completely. There are certain signs to watch for that offer clues that the battery could be on the way out. In some Audi models, for instance, an illuminated key and battery symbol on the dashboard is a definite sign that the battery is failing. For models that don't have this function, an intermittently working key fob is a good indicator.

Changing the battery on an Audi key fob is a fairly simple operation, and an Audi dealer can do it in a few minutes. However, if you don't have access to a dealership or would prefer to do it yourself, then this guide will walk you through the process.

One thing to note here is that the process will vary depending on the model of Audi you're working on. However, the following guidance features general steps that cover most models. If you're in any doubt, refer to the owner's manual or consult a dealer before proceeding.

Choosing the right battery is an obvious first step. The most common batteries used are the CR2032 type, although it's worth checking this beforehand, as some older models will require two CR1620 batteries. Additionally, always opt for high-quality batteries, or you can end up changing batteries frequently. Once you have the battery, it's time to install it.

However, there are some other things you can do beforehand: The first is to prepare a work area. There is an outside chance that any spring-loaded parts make a bid for freedom when you open the fob. Although this is unlikely, a well-lit and uncluttered work area will make sure any such part is easily located. Another useful and sometimes essential item is a small flat-headed screwdriver. This is often required for prying the key fob open. Additionally, it's good practice to use powderless safety gloves, which prevents oils and dust from getting onto electric contacts. 

There are three main types of Audi key fob: the slim key fob, the switchblade key fob, and the flat key fob, the following sections cover these individually. 

There are a couple of Audi switchblade key fob types, depending on the age of your vehicle. The one pictured is the older model, and does require a little more patience to access the battery, but both will require a small flat-headed screwdriver. This key fob is the oldest in the range, and covers models including the Q3, S3, RS3, and a host of others. The following instructions walk you through the process of swapping batteries for both switchblade key variants.

1. On the older model, make sure that the key is in the opened position. This isn't required in newer models. 
2. Take the flat headed screwdriver and pry open the casing. This method varies depending on the key type: 
   1. The newer version is simply a matter of inserting the screwdriver into the slot located on the back of the key, beside the keyring attachment, and gently prying upwards to open the panel and reveal the battery. 
   2. The older model (pictured above) requires inserting the screwdriver into a slot on the key surface, and gently prying upwards. The screwdriver can then be used to gently slide the two parts of the key apart until they separate, as shown above. 
3. The battery can now be changed and the panel replaced, or the two sections slide back together, depending on the type of fob. 

The slim key fob is Audi's most recent model, and is used in the vast majority of newer vehicles. Among the models covered are the A-range, S-range, and Q-range models from 2019 onwards, as well as the Audi e-tron models. A3, S3, and RS3 models didn't begin using this key until 2022 models and up. The following steps describe how to change the battery in an Audi slim key fob. 

1. Push the key release button located on the back of the fob, and remove the key from its enclosure. 
2. Inside the key fob, next to where the key release button is located, there is a small tab; this needs to be released. The key doubles as a tool for doing this, but a small flat-headed screwdriver works as well. Insert it slightly and at an angle to release the tab, and gently push upwards. Don't worry if it doesn't release the first time, it may require a bit of patience and finesse to get it open. 
3. Once the tab is successfully removed, the back panel is released and can be removed from the fob.
4. The battery can now be replaced, and the back panel refitted by locating the guides on the bottom of the panel in the key fob, and snapping the cover closed. 

The flat key fob — or "side" key fob as it is sometimes called — is commonly used on models that include the Audi TT range, Q7, A4, SQ5, and S5, among others. Although there are no tools required for this, the mechanism to access the battery can be awkward to engage. A little patience and some gentle perseverance may be required here when opening up the fob.

1. Push the two tabs located on either side of the fob, and remove the key from its enclosure. 
2. Once the key is released comes the tricky part. Underneath where the key housing sat, you will find two small spring-loaded tabs. These need to be simultaneously depressed while pulling the outwards to slide the battery-holder out of the housing. 
3. Once released, the battery can be popped out and the new one can be inserted. From there, the fob can then be re-assembled. 

It is possible that after changing your battery the key fob will no longer recognize your car. In these instances, the key fob will need to be paired with the vehicle. The process is fairly simple, although it's always best to check your user manual or the internet first, as the actual steps can vary by model. Two common methods are detailed below.

Method one:

1. Access the physical key located in your key fob. This varies depending on the key fob type. 
2. Insert it into the driver's door and use it to unlock and lock the door. 
3. Remove the key from the lock and press the unlock switch. If the procedure worked, your vehicle should unlock.

Method two: 

1. While sitting in the driver's seat, press and hold the unlock button — keep this button depressed throughout the operation. 
2. Insert the key into the ignition (remember to keep holding the unlock button).
3. Turn the key to the ON position for a couple of seconds. 
4. Return the key to the OFF position.
5. Remove the key from the car's ignition.
6. Release the unlock button, and then test to see if the procedure has worked.