The battery in your Audi key fob lasts three to four years before it needs replacing
When your Audi key fob stops locking or unlocking your car reliably, the battery is almost always the culprit. Replacing it takes about five minutes and costs between $5 and $15 for the battery itself. You do not need to visit a dealer or call a technician—you can do this at home with a coin and the correct battery type.
The most common Audi key fob batteries are CR2032 or CR2025 coin cells, depending on your model year and fob design. Before you start, identify which battery your fob uses so you buy the right one. You can find this information in your owner's manual, or you can open the fob and look at the old battery to see the code printed on it.
Key Takeaways
- Audi key fobs typically use CR2032 or CR2025 coin cell batteries, which you can buy at any pharmacy, grocery store, or electronics retailer for $5 to $15.
- The fob opens with a flat coin or plastic pry tool inserted into the seam on the edge—push gently to avoid cracking the plastic.
- 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 inserting the new battery, press the fob halves together until they click, then test the lock and unlock buttons before you leave.
Locate the seam and open the fob
Look at the edge of your key fob for a thin seam running around the perimeter. This seam marks where the two plastic halves meet. On most Audi fobs, the seam runs along the side or bottom edge. Insert a flat coin (a dime or penny works well) or a plastic pry tool into this seam, positioning it so the edge of the coin sits in the groove.
Gently twist the coin or tool to create leverage, explore steady pressure rather than sudden force. The two halves should separate with a soft click. If the fob resists, try a different spot along the seam—sometimes one side opens more easily than the other. Do not pry aggressively, as the plastic can crack and the fob will no longer seal properly.
Remove the old battery and note its position
Once the fob is open, you will see the battery sitting in a metal holder or slot. The battery is a small, flat, coin-shaped disc. Before you touch it, note which side is facing up—the positive side (marked with a + symbol) or the negative side (marked with a − symbol). This matters because installing the battery upside down will prevent the fob from working.
Slide the battery out of its holder by gently pushing it sideways or lifting it straight up, depending on how it sits. Some fobs have a small metal clip holding the battery in place; if yours does, lift the clip slightly first. Once the old battery is out, set it aside. Do not throw it away yet—you may need to check the model number if you are unsure which replacement to buy.
Buy and insert the correct replacement battery
Take the old battery to a pharmacy, grocery store, or electronics retailer and buy an identical replacement. The model number (CR2032, CR2025, etc.) is printed on the battery itself. If you cannot find the exact match, ask a store employee—they can usually identify the correct battery in seconds. Coin cell batteries are inexpensive and widely stocked.
Insert the new battery into the holder with the positive side facing the same direction as the old battery was facing. Slide it in gently until it sits flat in the holder. If your fob has a metal clip, make sure the clip holds the battery securely in place. 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 lines up evenly all the way around. Press them together firmly until you hear or feel a click. The fob should close with a solid snap, not a loose fit. If it does not close completely, open it again and check that the battery is sitting flat and the plastic edges are not bent.
Once the fob is closed, test the lock and unlock buttons. Point the fob at your car and press each button a few times. You should see the lights flash and hear the locks engage. If the buttons do not work, open the fob again and check that the battery is installed with the correct side facing up. If it is, the battery may be defective—try a fresh one from a different package.
Common mistakes that prevent the fob from working
The most frequent error is installing the battery upside down. The positive side must face the same direction as it did in the old battery. If you are unsure, open the fob again and flip the battery 180 degrees, then test the buttons. Another common mistake is not closing the fob completely—if the halves are not fully seated, the battery may lose contact with the terminals inside.
Occasionally, the battery holder itself becomes corroded or the metal contacts inside the fob are dirty. If you have installed a fresh battery with the correct polarity and the fob still does not work, try cleaning the metal contacts inside the fob with a dry cotton swab or a pencil eraser. Gently rub the contacts where the battery touches the holder, then insert a new battery and test again.
When to replace the battery again
A new coin cell battery typically lasts three to four years in an Audi key fob, depending on how often you use the fob. If you use the fob multiple times every day, the battery may last closer to two years. If you use it sparingly, it may last longer. When the fob begins to work intermittently—locking sometimes but not always—that is a sign the battery is weakening and a replacement is due soon.
Keep a spare CR2032 or CR2025 battery in your car or at home so you can replace the fob when ready if it fails. This is much faster than waiting for a dealer appointment or ordering a battery online. Since the replacement takes only a few minutes, you can swap batteries anywhere—in a parking lot, at home, or at work.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact model?
No. Using the wrong battery type can damage the fob or prevent it from working. CR2032 and CR2025 are not interchangeable—they have different thicknesses. Always buy the exact model number printed on your old battery. If a store does not have it in stock, ask them to order it or try another retailer.
What if the fob still does not work after I replace the battery?
First, open the fob and check that the battery is installed with the positive side facing the correct direction. If it is, try cleaning the metal contacts inside the fob with a dry cotton swab. If the fob still does not work, the problem may be inside the fob itself—a broken button or damaged circuit board—and you may need to have it serviced or replaced by an Audi dealer.
Is it safe to replace the battery myself, or should I go to a dealer?
It is completely safe to replace the battery yourself. The fob contains no dangerous components, and the battery is a standard consumer item. Dealers charge $50 to $100 for the same five-minute job. Replacing it at home saves time and money with no risk.
How do I know which battery my Audi key fob uses?
Check your owner's manual, or open the fob and look at the old battery—the model number is printed on it. You can also call an Audi dealer with your vehicle's year and model, and they will tell you the correct battery type. Most Audi fobs use CR2032, but some older models use CR2025.
Can I buy batteries in bulk and store them for later?
Yes. Coin cell batteries have a long shelf life when stored in a cool, dry place. Buying a pack of five or ten CR2032 batteries is cheaper per unit than buying one at a time, and you will always have a spare on hand when your fob battery dies.