What battery your Audi key fob uses and where to find it
Most Audi key fobs use a CR2032 coin cell battery, the same flat, round battery you find in watches and calculators. Some older Audi models use CR2025 or CR2016 instead, so check your owner's manual or the fob itself before you buy. The battery costs between $3 and $8 at any pharmacy, supermarket, or hardware store.
You can identify which battery your fob needs by looking at the back or side of the fob itself — the battery type is usually printed there. If you cannot read it clearly, your Audi dealer can tell you over the phone with your vehicle identification number (VIN), or you can open the fob and look at the old battery directly.
Key Takeaways
- Audi key fobs almost always use CR2032 batteries, which cost a few dollars and are sold everywhere.
- You can open most Audi fobs by sliding a flat tool into the seam on the edge and gently twisting 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.
- Newer Audi fobs may require a small screwdriver to open; check your manual if the sliding method does not work.
- If the fob still does not work after a new battery, the problem is likely the circuit board or buttons, not the battery itself.
How to open your Audi key fob safely
The most common Audi fob design opens by sliding a flat tool into the seam that runs around the edge of the fob. Use a flathead screwdriver, a coin, or a plastic pry tool — avoid anything sharp that could scratch the fob or damage the internal clips. Insert the tool into the seam on the side opposite the buttons and gently twist to explore pressure; the two halves should separate with light resistance.
Do not force it. If the fob does not budge after gentle pressure, stop and check your owner's manual — some newer Audi models have a small screw hidden under a rubber pad on the back, or a release button on the side. Forcing an unopenable fob can crack the plastic or break the clips that hold it together.
Once the fob is open, you will see the battery sitting in a metal holder. The holder usually has a small lip or edge you can use to slide the battery out sideways. Note which side of the battery faces up — the positive side (marked with a plus sign) should face the same direction as it did before.
Removing and replacing the battery
Slide the old battery out of its holder by pushing gently on the edge opposite the lip. The battery should come free without much force. If it is stuck, do not pry at it — a stuck battery usually means the holder is slightly bent, and forcing it can damage the holder or the circuit board underneath.
Before you insert the new battery, wipe both sides with a clean, dry cloth. Dust or moisture on the battery can prevent good contact and cause the fob to work intermittently. Slide the new battery into the holder with the positive side (the plus sign) facing the same direction as the old one faced. You should hear or feel a small click as the battery seats in the holder.
Close the fob by pressing the two halves together firmly until they snap. You may hear a click or feel resistance as the clips engage. Do not force it — if the halves do not come together smoothly, open it again and check that the battery is seated correctly and nothing is blocking the seam.
Testing your key fob after the battery change
Stand near your Audi and press each button on the fob — lock, unlock, trunk, and panic if your model has one. You should see the lights flash on your car and hear the locks respond. If nothing happens, open the fob again and check that the battery is installed with the correct side facing up. The positive side (marked with a plus) must face toward the circuit board.
If the fob still does not work after you have checked the battery direction twice, the problem is likely not the battery. The circuit board, the buttons, or the contacts inside the fob may be damaged or worn. At that point, you will need a replacement fob from your Audi dealer or an aftermarket supplier.
When to replace the entire fob instead
If your fob is cracked, the buttons are stuck or unresponsive, or water has gotten inside, a new battery will not fix it. Water damage is common in key fobs — if you have dropped it in water or spilled liquid on it, the circuit board may be corroded even if the fob looks dry on the outside. Opening it and letting it air-dry for 24 hours in a warm place can sometimes help, but there is no may provide.
Audi dealers sell replacement fobs that are already programmed to your car, though they are expensive — usually $200 to $400 depending on the model year and features. Aftermarket fobs are cheaper but may require programming, which some dealers charge for separately. If your fob is old and has other problems besides the battery, replacing it may be more practical than repairing it.
Preventing battery drain and fob problems
Key fob batteries last two to four years with normal use. You can extend that time by keeping the fob away from extreme heat, moisture, and direct sunlight. Do not leave it in a hot car or in a pocket near your body heat for long periods. If you notice the fob is less responsive than usual — the buttons require harder pressing, or you have to be closer to the car for it to work — the battery is probably running low, and a fresh one will restore full range.
If you have multiple fobs for the same car, rotate which one you use most often. This spreads the battery drain across all of them and means you are less likely to have a dead fob when you need it. Keep a spare fob in a drawer at home so you always have a backup if one fails.
Frequently Asked Questions
Can I use a different battery size if I cannot find CR2032?
No. CR2032, CR2025, and CR2016 are different thicknesses and will not fit the holder correctly or make proper contact. Buy the exact size your fob needs. If your local store is out of stock, order online — they ship quickly and cost only a few dollars.
Why does my fob work sometimes but not always after the battery change?
The battery is probably installed upside down, or the contacts inside the holder are dirty. Open the fob, flip the battery so the plus sign faces the circuit board, and wipe both the battery and the metal contacts with a clean cloth. If it still works intermittently, the contacts may be corroded and the fob may need replacement.
Do I need to reprogram my fob after changing the battery?
No. Changing the battery does not erase the programming. Your fob should work when ready after you close it. If it does not, the problem is the battery installation or the fob itself, not the programming.
What should I do if I cannot open my Audi fob?
Check your owner's manual — some models have a hidden screw or a release button you cannot see. If you still cannot open it, your Audi dealer can open it for you, usually for free or a small fee. Do not use excessive force, as you can crack the plastic or break the internal clips.
Is it safe to open my key fob myself?
Yes, as long as you use gentle pressure and the right tools. Use a plastic pry tool or a coin rather than a sharp screwdriver, and stop if you feel strong resistance. The fob contains no dangerous parts — just a battery, a circuit board, and plastic. The biggest risk is breaking the plastic clips that hold it together.