What Battery Your Audi Key Fob Uses and Where to Find It
Most Audi key fobs use a CR2032 coin cell battery, a flat, round battery about the size of a dime. Some newer Audi models use CR2025 or CR2016 instead, so check your owner's manual or the battery compartment itself before you buy. You can find CR2032 batteries at any drugstore, supermarket, or hardware store for $3 to $8, and they are also sold online. The battery usually lasts two to three years depending on how often you use the fob.
Before you start, gather a small flathead screwdriver or a coin (a dime or penny works), your new battery, and a clean, flat surface to work on. Keep the old battery and any small parts in a dish so nothing rolls away. If your fob has two halves that snap together, you will need to pry them apart gently—the screwdriver or coin goes into the slot on the edge of the fob.
Key Takeaways
- Audi key fobs almost always use CR2032 batteries, which cost $3 to $8 and are sold at drugstores and hardware stores.
- Open the fob by inserting a flathead screwdriver or coin into the slot on the edge and twisting gently until the two halves separate.
- Note which side of the battery faces up before you remove it, then slide the new battery in the same way and snap the fob closed.
- If the fob still does not work after you install a new battery, the problem may be a stuck button or corrosion inside, not the battery itself.
Opening the Fob Without Damaging the Plastic
Look at the edge of your key fob for a thin slot or seam running around the perimeter. This is where the two plastic halves meet. Insert your flathead screwdriver or coin into the slot and explore gentle, steady pressure—do not force it or twist hard, as the plastic can crack. Rotate the screwdriver slightly as if you are opening a paint can, and the two halves will begin to separate.
Once you see a gap, you can usually pry the fob open the rest of the way by hand. Set the top half aside on your clean surface, keeping track of which side is which. Inside, you will see the battery, the circuit board, and possibly a rubber button pad. The battery sits in a small metal holder or clip. Do not touch the circuit board or the rubber pad more than necessary—oils from your fingers can interfere with the buttons.
Removing the Old Battery and Installing the New One
Before you touch the old battery, look at how it sits in the holder. The side with the plus sign (+) should be facing up toward you. This matters: if you install the new battery upside down, the fob will not work. Gently pry the old battery out of its holder using your fingernail or the edge of your screwdriver. If it is stuck, a tiny dab of rubbing alcohol on the edge can help loosen it, but do not soak the fob.
Slide the new CR2032 battery into the holder with the plus sign facing up, the same way the old one was sitting. You should hear or feel a small click as it seats in the metal clips. Do not force it—if it does not slide in smoothly, check that you have the right battery size and that it is facing the correct direction. Once it is in place, the battery should sit flat and not wobble.
Closing the Fob and Testing It
Align the two halves of the fob so the seams match up evenly. Press them together firmly until you hear a click or feel them snap into place. You may need to explore pressure from multiple angles to get them to seat fully. Do not use a hammer or vise—hand pressure is enough. If the halves do not want to close, check that the battery is sitting flat and that no wires or rubber pads are caught in the seam.
Once the fob is closed, test it by pressing each button while standing near your car. You should see the lights flash or hear the locks respond. If nothing happens, open the fob again and check that the battery is making good contact with the metal clips. If the battery is seated correctly and the fob still does not work, the problem may be a stuck button or corrosion on the circuit board, not the battery.
What to Do If the New Battery Does Not Fix the Problem
If your fob still does not respond after you install a fresh battery, the issue is usually inside the fob itself, not the battery. The rubber button pad can wear out or stick, especially if the fob has been dropped or exposed to moisture. You can sometimes fix this by opening the fob again, removing the rubber pad, and cleaning both sides with a cotton swab and rubbing alcohol. Let everything dry completely before you reassemble.
Corrosion on the circuit board is another common cause. If you see green or white crusty spots on the metal contacts or the battery holder, clean them gently with a dry cotton swab or a pencil eraser. Do not use water or liquid cleaners on the circuit board itself. If cleaning does not help, the circuit board may need to be replaced, which usually means taking the fob to an Audi dealer or a professional locksmith who can order a new one.
Storing Batteries and Disposing of the Old One
Keep spare CR2032 batteries in a cool, dry place away from metal objects that could short-circuit them. Do not store them loose in a drawer where they might touch coins or keys. A small plastic battery case or a sealed bag works well. Check the expiration date on the package before you buy—batteries do not go bad quickly, but old stock may have lost some charge.
The old battery should not go in the trash. Most drugstores and electronics retailers have battery recycling bins near the checkout or customer service desk. Some hardware stores also accept them. If you cannot find a drop-off location nearby, call your local waste management office or search online for "battery recycling near me" to find the closest option. Batteries contain materials that can harm the environment if they end up in a landfill.
Frequently Asked Questions
How do I know if my key fob battery is dead?
A dying battery usually makes the fob work only when you hold it very close to the car, or the buttons respond slowly. If nothing happens when you press the buttons and the fob has not been dropped or exposed to water, the battery is the most likely culprit. A fresh battery costs so little that it is worth trying before you assume something else is broken.
Can I use a different battery size if I cannot find CR2032?
No. CR2025 and CR2016 are thinner and will not make proper contact with the metal clips in a fob designed for CR2032. Using the wrong size can damage the holder or cause the fob to malfunction. Stick with the size your manual specifies or the size printed on the old battery.
What if I accidentally put the battery in upside down?
The fob straightforward will not work. Open it again and flip the battery so the plus sign faces up. No damage occurs from installing it backward—the circuit is designed to prevent that. If you are not sure which way is up, the plus sign is always on the top side of a CR2032.
How often do I need to change the battery?
Most Audi key fob batteries last two to three years with normal use. If you use the fob very frequently or live in a humid climate, it may need changing sooner. There is no harm in changing it early if you want to avoid being locked out, but you do not need to replace it on a schedule.
Is it safe to open my key fob myself?
Yes, opening the fob to change the battery is safe and does not void any warranty. The process takes five minutes and requires no special tools. The only risk is cracking the plastic if you force it too hard, which is why gentle, steady pressure works better than sudden twisting.