Open the key fob without damaging it
Most Audi key fobs split into two halves along a seam that runs around the edge. Look for a small slot or groove on the side of the fob — this is where you insert a flat tool to pry the halves apart. A flathead screwdriver, a coin, or a plastic pry tool all work. Insert the tool gently into the slot and twist slightly; you should feel the two halves separate.
Do not force the fob open. If it resists, you may be prying at the wrong spot. Rotate the fob and try a different section of the seam. Once the halves separate, you will see the battery sitting in a plastic holder, usually in the center of one half.
Key Takeaways
- Audi key fobs typically use a CR2032 or CR2025 battery, which you can buy at any drugstore, supermarket, or hardware store for two to five dollars.
- Open the fob by inserting a flat tool into the seam and twisting gently — do not force it, as the plastic cracks easily.
- Note which side of the battery faces outward before you remove it, because the new battery must go in the same way.
- After inserting the new battery, press the fob halves together until they click, and test all buttons to confirm the fob works.
Identify and remove the old battery
The battery sits in a small plastic holder or slot. Look at which side faces up — the positive side (marked with a +) or the negative side (marked with a −). Take a photo with your phone if you are unsure, because you must install the new battery the same way.
Gently pry the battery out of its holder using your fingernail or a plastic tool. Do not use a metal screwdriver directly on the battery, as this can damage it. Once the battery is out, set it aside.
Buy the correct replacement battery
Audi key fobs use either a CR2032 or CR2025 battery. The easiest way to know which one you need is to check the number printed on the old battery you just removed. If you cannot read it clearly, CR2032 is the most common choice for Audi fobs made in the last ten years.
You can buy either battery at a pharmacy, supermarket, dollar store, or hardware store. They cost between two and five dollars. Some stores sell them in multipacks, which is useful if you have other devices that use the same battery.
Insert the new battery correctly
Place the new battery into the holder with the same side facing up as the old one. If the positive side was facing up before, the positive side should face up now. Press down gently until the battery sits flat in its holder. You should feel it settle into place.
Do not force the battery down. If it does not sit flat, remove it and check that you are inserting it the correct way. A battery installed backward will not work, but it will not damage the fob either — you straightforward remove it and flip it over.
Close the fob and test it
Align the two halves of the fob so the seam lines up evenly all the way around. Press them together firmly until you hear or feel a click. The halves should be flush with each other with no gaps.
Test the fob by pressing each button — lock, unlock, trunk, and panic if your model has one. All buttons should work when ready. If a button does not respond, open the fob again and check that the battery is seated properly and facing the correct direction. Close it again and test once more.
What to do if the fob still does not work
If the fob does not work after you install a new battery, the battery may be defective. Try a different battery from a different package or store. Batteries occasionally arrive dead, especially if they have been sitting on a shelf for a long time.
If a second battery also does not work, the fob itself may have a problem — a broken button contact, water damage, or a failed circuit board. In this case, you will need to contact an Audi dealer or a locksmith who makes car keys. They can test the fob and replace it if necessary. Replacement fobs typically cost between one hundred and three hundred dollars depending on your model year.
How often to change the battery
A CR2032 battery in an Audi key fob usually lasts between three and four years with normal use. You may notice the buttons becoming less responsive before the battery dies completely — this is a sign the battery is weakening. When this happens, replace it right away rather than waiting for the fob to stop working entirely.
If you use your fob very frequently — pressing the buttons many times per day — the battery may wear out faster, sometimes in two to three years. If you use it rarely, it may last longer. Storing the fob in a cool, dry place helps the battery last as long as possible.
Frequently Asked Questions
Can I use a different type of battery?
No. Audi key fobs are designed for either CR2032 or CR2025 batteries, and these are not interchangeable with other types. Using the wrong battery size will not fit in the holder or will not power the fob correctly. Always check the number on your old battery before buying a replacement.
What if I lose the old battery before I can check the number?
CR2032 is the standard battery for most Audi fobs. Buy a CR2032 first and try it. If it does not fit or does not work, return it and buy a CR2025 instead. Most stores accept returns on batteries even if they are opened.
Is it safe to handle the battery with my bare hands?
Yes. Coin cell batteries like CR2032 are safe to touch with your bare hands. Wash your hands after handling if you prefer, but there is no risk from normal contact. Do not swallow the battery or let children play with it, as swallowing can cause internal burns.
Do I need to reprogram the fob after changing the battery?
No. Changing the battery does not erase any programming. The fob will work when ready after you close it and install the new battery. You only need to reprogram a fob if you have lost it or if Audi has reprogrammed your car's locks.
How do I know if my fob uses CR2032 or CR2025?
Open the fob and look at the number stamped on the old battery. It will say either CR2032 or CR2025. If you cannot read it, CR2032 is more common. You can also call your Audi dealer with your vehicle identification number (VIN) and they will tell you which battery your model uses.