The battery in your Audi key fob lasts three to four years, then needs replacing
When your Audi key fob stops locking or unlocking the car reliably, the battery is usually dead. You do not need a dealer visit or special tools — you can open the fob yourself and swap in a new battery in under five minutes. The part costs between $5 and $15, and the process is the same across most Audi models from the last 15 years.
Audi key fobs use a coin-cell battery, typically a CR2032 or CR2025 depending on your model year. You can buy these at any pharmacy, supermarket, or hardware store. The fob itself is designed to come apart by hand, though you may need a small flathead screwdriver or a coin to help pry the seam open.
Key Takeaways
- Audi key fobs use a CR2032 or CR2025 coin-cell battery that you can buy at any drugstore for $5 to $15.
- The fob opens by inserting a flathead screwdriver or coin into the seam on the side and twisting gently to separate the two halves.
- The battery sits in a metal holder and slides out sideways — note which side faces up before you remove it so you install the new one the same way.
- After you close the fob, test the lock and unlock buttons before you leave the parking lot to confirm the new battery works.
Identify which battery your Audi key fob uses
Most Audi key fobs from 2008 onward use a CR2032 battery. If your car is older than that, or if you want to be certain before you buy, check your owner's manual — it will list the battery type in the key fob section. You can also call your Audi dealer with your vehicle identification number (VIN) and they will tell you over the phone at no charge.
If you cannot find the manual or reach the dealer, buy a CR2032 first. It is the most common size. If it does not fit, the CR2025 is the only other option Audi uses, and you can exchange it at the store where you bought it.
Open the key fob without damaging the case
Look at the edge of your key fob where the two halves meet. You will see a thin seam running around the perimeter. Insert a flathead screwdriver or the edge of a coin into this seam on the side opposite the Audi logo. Do not force it — you are looking for the spot where the two halves are designed to separate.
Once the screwdriver or coin is seated in the seam, twist gently. You should feel the fob begin to flex slightly. Keep twisting until one half pops free. Set the metal battery holder and circuit board aside on a clean surface where you will not lose small parts. The rubber button pad usually stays attached to one half of the plastic case.
Remove the old battery and note its orientation
The battery sits in a metal holder with two small tabs. Before you touch it, look at which side is facing up — the positive side (marked with a + symbol) or the negative side (marked with a − symbol). Take a photo with your phone if you want to be certain you get it right.
Slide the battery out of the holder sideways. Do not pry it straight up, as you may damage the holder. Once it is out, you can discard it or recycle it at a pharmacy or electronics store. Wipe the inside of the holder with a dry cloth to remove any dust or corrosion.
Install the new battery the same way the old one faced
Take your new CR2032 or CR2025 battery and slide it into the metal holder, positive side facing the same direction as the old battery faced. You should hear or feel a small click as it seats. Do not force it — if it does not slide in smoothly, you may have the polarity backwards. Flip it and try again.
Once the battery is seated, gently press down on it to make sure it is making contact with both tabs in the holder. The battery should not move or rattle when you shake the fob lightly.
Close the fob and test the buttons
Align the two halves of the fob so the seam is even all the way around. Press them together firmly until you hear a click. The fob should feel solid and not flex when you squeeze it gently. If there is a gap or it feels loose, open it again and check that the battery holder and circuit board are seated all the way down.
Stand near your car and press the lock button on the fob. The car should lock and the lights should flash. Press unlock and listen for the unlock sound. If both buttons work, the battery is installed correctly and you are done. If nothing happens, open the fob again and check that the battery is facing the right direction.
What to do if the fob still does not work after replacing the battery
If you installed a new battery and the fob still does not respond, the problem is usually not the battery. The most common cause is corrosion inside the battery holder or on the circuit board contacts. Open the fob again and look for white, green, or blue discoloration on the metal tabs or the circuit board. If you see corrosion, dab it gently with a cotton swab barely dampened with white vinegar, then dry it completely before reinstalling the battery.
If there is no corrosion and the battery is definitely facing the right way, the circuit board itself may be damaged. This is rare, but it means the fob needs to be replaced. Contact your Audi dealer for a replacement fob — they can order one and program it to your car, though this will cost more than a battery replacement.
Frequently Asked Questions
Can I use a different battery size if I cannot find a CR2032?
No. A CR2025 is slightly thinner and may work in some Audi fobs, but a CR2016 or any other size will not fit the holder. Stick with CR2032 first, and only try CR2025 if the 2032 does not fit. Do not use alkaline batteries — they are the wrong shape and voltage.
How long does a new battery last in an Audi key fob?
A CR2032 battery typically lasts three to four years in normal use. If you use the fob frequently or live in a very cold climate, it may last only two to three years. There is no way to predict exactly when it will die, but you will notice the buttons becoming less responsive before the battery is completely dead.
What if I lose a small part when I open the fob?
The rubber button pad and the metal battery holder are the only parts that can fall out. If you lose the rubber pad, the buttons will still work but may feel mushy. You can order a replacement pad from Audi or an online parts supplier for $10 to $20. If you lose the metal holder, the fob will need to be replaced.
Do I need to reprogram the fob after changing the battery?
No. The fob does not need reprogramming after a battery change. As soon as the new battery is installed and making contact, the fob will work exactly as it did before. If it does not work when ready, the problem is the battery orientation or a damaged circuit board, not a programming issue.