Open the key fob and remove the old battery
Most Audi key fobs split into two halves with a small slot on the edge. Insert a flat tool—a coin, flathead screwdriver, or the edge of a butter knife works—into the slot and twist gently. The fob will pop apart, revealing the battery held in a metal clip or plastic holder.
Note which direction the battery sits before you remove it. The flat side (negative) and the rounded side (positive) matter for the new battery to work. Slide or pry the old battery out of its holder. If it's stuck, a small plastic pry tool or old credit card can help without scratching the fob's interior.
Key Takeaways
- Audi key fobs use CR2032 batteries, which cost $3 to $8 and are sold at pharmacies, supermarkets, and hardware stores.
- Open the fob by inserting a flat tool into the slot on the edge and twisting gently until the two halves separate.
- Install the new battery with the positive (rounded) side facing up, matching the position of the old battery.
- Test the fob before reassembling by pressing each button and listening for the click that means the battery contacts are working.
- If the fob still does not work after a new battery, the contacts may be dirty—clean them with a pencil eraser or rubbing alcohol on a cotton swab.
Identify the correct battery type for your Audi
Audi key fobs use a CR2032 battery, a coin-shaped lithium cell 20 millimeters across and 3.2 millimeters thick. This is the most common button battery sold in the United States. You will find it at any pharmacy (CVS, Walgreens), supermarket, or hardware store in the battery aisle, usually near the checkout counter.
A CR2032 costs between $3 and $8 depending on the brand and where you buy it. Name-brand batteries (Duracell, Energizer) cost more than store-brand versions, but they all work the same way in a key fob. Do not buy a different battery size—CR2025 or CR2016 look similar but are thinner and will not make proper contact inside the fob.
Install the new battery in the correct direction
Slide the new CR2032 into the holder with the positive side (the flat, shiny side marked with a plus sign) facing up, matching the direction the old battery was sitting. Push it down until it clicks or seats firmly in the metal clip. The battery should not move when you gently shake the open fob.
If the battery does not sit flat or feels loose, remove it and check that the holder is not bent or blocked by debris. A small piece of lint or corrosion can prevent the battery from seating. Wipe the holder with a dry cloth if needed, then try again.
Test the fob before closing it
Before you snap the two halves back together, press each button on the fob—lock, unlock, trunk, and panic if your model has one. You should hear a soft click each time, which means the battery is making contact with the circuit board. If you hear nothing, the battery may not be seated correctly. Remove it, check the direction, and reinstall it.
If the buttons click but the fob still does not work after you close it, the problem is usually dirty battery contacts. Open the fob again and look at the metal contacts on the circuit board—they may be black or corroded. Rub them gently with a pencil eraser or a cotton swab dipped in rubbing alcohol, then let them dry for a minute before reinstalling the battery.
Reassemble the key fob
Line up the two halves of the fob so the edges match evenly. Press them together firmly until you hear or feel a click. The fob should be solid with no gaps. If it does not close smoothly, remove it and check that the battery is not sticking up too high or that no wires are pinched between the halves.
Once closed, test the fob again by pressing each button and watching for your car to respond—lights should flash, doors should lock or unlock, and the trunk should open. If the fob works now but did not work when you tested it open, the problem was likely dirty contacts, and the erasing or alcohol cleaning fixed it.
Troubleshoot if the new battery does not work
If your Audi still does not respond after installing a new CR2032 and cleaning the contacts, the fob's circuit board may be damaged or the receiver in your car may need attention. Try the fob on a different Audi if you have access to one—if it works, the problem is with your car's receiver, not the fob. If it does not work on any car, the fob itself needs replacement.
Before you assume the fob is broken, check that you bought a CR2032 and not a similar-looking battery. Hold it up to the light and compare it to the package—the size and thickness must match exactly. Also confirm that the battery is not expired; check the date printed on the package or the back of the battery itself.
When to replace the entire key fob
A battery change usually solves a dead Audi key fob, but sometimes the fob itself has failed. Signs of a broken fob include buttons that stick or do not click, cracks in the plastic case, or water damage (the fob was dropped in water or exposed to heavy rain). If the fob has physical damage, a new battery will not help.
Audi dealerships sell replacement key fobs, and independent locksmiths often stock them as well. Prices vary by model year and region, but expect to pay $150 to $400 for a new fob from a dealership and $80 to $250 from a locksmith. Some locksmiths can also program a used fob from a salvage yard for less money if your car's receiver is working.
Frequently Asked Questions
How long does a CR2032 battery last in an Audi key fob?
A CR2032 typically lasts three to four years in normal use, though heavy use can shorten that to two years. If you use your key fob many times per day, you may need to change the battery sooner. Store-brand and name-brand batteries have similar lifespans.
Can I use a rechargeable battery in my Audi key fob?
No. Rechargeable CR2032 batteries are weaker than disposable ones and may not provide enough voltage to trigger your car's receiver reliably. Stick with a standard disposable CR2032 for consistent performance.
What if I lost the small tool to open my key fob?
Any flat, thin object works—a coin, butter knife, old credit card, or flathead screwdriver. Insert it gently into the slot on the edge of the fob and twist slowly. Do not force it or you may crack the plastic. If the slot is too tight, try a thinner tool.
Is it safe to open my Audi key fob myself?
Yes. Opening the fob to change the battery is safe and does not void any warranty. The fob contains only the battery, circuit board, and buttons—nothing that can hurt you. Just avoid getting water inside and do not force the halves apart.
Why does my key fob work sometimes but not always?
Intermittent fob problems usually mean the battery is dying or the contacts are dirty. A new battery often solves this. If a new battery does not help, clean the metal contacts inside the fob with a pencil eraser or rubbing alcohol on a cotton swab, then reinstall the battery.