You can replace an Audi key fob battery yourself in about five minutes
Most Audi key fobs use a coin-cell battery — usually a CR2032 or CR2025 — that you can buy at any drugstore, supermarket, or hardware store for a few dollars. The fob itself is designed to open without tools, so you do not need to visit a dealer or pay a service fee. The whole process takes longer to find the right battery size than to swap it out.
The steps are the same whether you have a newer Audi with a push-button start or an older model with a traditional key. The only variation is the exact location of the seam you pry open, which depends on your fob's shape and year.
Key Takeaways
- Audi key fobs typically use a CR2032 or CR2025 coin-cell battery that costs $3 to $8 and is sold at most retailers.
- You open the fob by gently prying along the seam between the two halves with a flat tool like a coin or plastic spoon.
- The battery sits in a small metal holder; note which side faces up before you remove it so you can install the new one the same way.
- After you close the fob, test all buttons — lock, unlock, trunk, and panic — to confirm the new battery is working.
Finding the right battery size for your Audi fob
Before you open the fob, you need to know which battery it uses. The easiest way is to check your owner's manual, which lists the battery type in the key fob section. If you do not have the manual, you can look up your model year and fob style on Audi's website or call a local Audi dealer and give them your vehicle identification number (VIN) — they will tell you the battery type without charging you.
CR2032 is the most common size for Audi fobs made in the last 15 years. CR2025 is less common but still appears in some older models. Both are standard coin-cell batteries sold in the battery aisle of drugstores, supermarkets, and online retailers. Buy a pack of two or three so you have a spare; they last three to four years in normal use.
Opening the key fob without damaging it
Look at your fob and find the seam that runs around the edge where the two plastic halves meet. On most Audi fobs, this seam runs horizontally across the middle, though some models have it on the side. You will see a small slot or indentation along this seam — this is where you insert a flat tool to pry the halves apart.
Use a coin, a plastic spoon, a butter knife, or a plastic pry tool. Do not use a sharp metal blade, which can scratch the plastic or slip and cut your hand. Insert the tool gently into the slot and twist it slightly to create a gap, then work your way around the seam. The two halves should separate with light pressure; if you are forcing it, you are probably prying in the wrong spot.
Once the fob is open, you will see the circuit board and the battery holder. The battery sits in a small metal cradle, usually on one side of the board. Do not touch the circuit board itself, and be careful not to drop any small parts.
Removing the old battery and installing the new one
Before you remove the old battery, look at which side is facing up — the positive side (marked with a + sign) or the negative side (blank). This matters because the battery only works one way. Take a photo with your phone if you want to be sure you remember.
Gently pry the old battery out of its metal holder using your fingernail or a plastic tool. Do not use a sharp metal object, which can damage the holder. Once the old battery is out, drop the new battery into the holder with the same side facing up as the old one. It should sit flat and snug in the cradle.
Closing the fob and testing 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 fob should close completely with no gaps. If it does not close smoothly, open it again and check that the battery is sitting flat in its holder and that no wires or plastic tabs are in the way.
Once the fob is closed, test every button: lock, unlock, trunk release, and panic (if your fob has one). Point the fob at your car from a few feet away and press each button. You should see the lights flash or hear the car respond. If nothing happens, open the fob again and check that the battery is installed correctly — the positive side should be facing up, and the battery should be sitting fully in its cradle.
What to do if the fob still does not work
If you installed a new battery and the fob still does not respond, the problem is usually not the battery. The circuit board may have water damage, or a button contact may be worn out. In that case, you have two options: buy a replacement fob from Audi or an aftermarket supplier, or take the fob to an Audi dealer for repair.
Replacement fobs range from $150 to $400 depending on the model and whether it includes a physical key blade. Aftermarket fobs are usually cheaper but may not have all the features of the original. A dealer can also reprogram a new fob to your car, which is required for some Audi models.
Frequently Asked Questions
How do I know if my key fob battery is dead?
A dead battery usually means the buttons do not respond at all, or they only work when you hold them down for several seconds. If the fob worked fine yesterday and stopped today, the battery is the most likely cause. If the fob has been working poorly for weeks — buttons getting slower or less responsive — the battery is probably running low.
Can I use a different battery size if I cannot find the right one?
No. CR2032 and CR2025 are different thicknesses, and using the wrong size can prevent the fob from closing properly or cause the battery to lose contact with the holder. Always use the exact size your fob requires. If your local store does not have it, order it online — it will arrive in one or two days.
Do I need to reprogram my Audi after changing the battery?
No. Changing the battery does not erase any programming. Your fob will work exactly as it did before, as long as the new battery is installed correctly and the fob was working before the battery died.
What should I do with the old battery?
Coin-cell batteries can be recycled. Many retailers that sell batteries — including drugstores and supermarkets — have a battery recycling bin near the checkout or customer service desk. You can also check Earth911.com to find a recycling center near you.