If you’re anything like me, the battery died on your first key fob a long time ago, and then you switched to your second backup key fob and now its battery has run out too – so it’s well past time to change the batteries.

You could have the dealer do it, where I’ve heard estimates range between $80-150 per key…or you could do it yourself for about $5 in under 5 minutes. Needless to say, I took the later route, and I’m here to tell you it’s very easy to do – simply press in two tabs on the key, pop off the back cover, replace the battery, and then press the rear cover back into place. You’ll also need to re-program the key, which is as simple as turning the car on/off 5 times.

This article applies to any keys that look like the one pictured above, most notably the B7 platform Audi A4, S4 or RS4, which was produced from 2005.5-2008. Other Audi models from this date range also share the same key, and the instructions should apply to those models too (although reprogramming the key for your car may differ slightly), however I can’t confirm which other models this applies to.

Supplies Needed:

  1. 1 CR2032 Battery (per key fob) – I purchased a 5 pack on Amazon for $5 which allowed me to replace the batteries on both of my key fobs as well as have a few extras for down the road, but you really only need 1 per key.
  2. A small flat-head screwdriver – those for eyeglasses work great, but any screwdriver should be fine. A pen would probably work if you’re in a pinch, but be careful not to do anything that would leave a mark or print on the key.
Step 1 - Press in Tab Where Key collapses

Step 1 – Press in Tab Where Key collapses

Step 1 – Press in the tab located along the side of the battery where the key folds in using your small flat head screwdriver. You’ll want to press it hard enough that the back cover starts to pop out.

Step 2 - Press in Tab on bottom of key

Step 2 – Press in Tab on bottom of key

Step 2 – Press in the second tab, located on the bottom of the key. You’ll want to press hard enough that the rear cover is pretty much completely popped off, and then you can simply just remove the cover with your fingers.

Step 3 - Pop out back cover

Step 3 – Pop out back cover, replace battery

Step 3 – Replace the battery, making sure the positive side of the battery is facing up.

Step 4 – Pop the rear cover back on the key fob, which can be done just by pressing the key back together (no tools needed)

Step 5 – You will probably need to reprogram the key. To do this simply insert your key into the car’s ignition, then turn it on/off 5 times (do not start the car, just turn it to the ON position right before a full start). This will reprogram the key.


  • If you do not see a red light when you press lock/unlock on the key fob, either the battery is installed incorrectly, the battery is dead, or there is some other issue with your key fob (e.g. water damage) preventing it from sending a signal. Replace the battery and be sure to have the positive side of the batter facing outward, and then order a new key fob if that does not work.
  • If a red light appears when you hit lock/unlock on your key fob, but the doors do not lock/unlock, you need to reprogram your key to the car. The reprogramming process may vary by your specific model, so if you do not have a B7 platform Audi A4, S4 or RS4, try Googling the instructions for your specific car.