1. Get the right battery first
Open the key and read the code on the old battery, or look up your model here. Most car keys take a CR2032, but not all.
2. Take out the metal key
Press or slide the small release button and pull out the metal key. Behind it there is usually a slot for opening the case.
3. Open the case gently
Twist the tip of the metal key or a small screwdriver wrapped in tape in the slot. Don’t force the seam, or you’ll leave marks and can snap a clip.
4. Copy the old battery’s position
Note which side faces up before you take the old battery out. Hold the new one by its edges and put it in the same way.
5. Close it and test
Press the halves together until every clip clicks. Then try lock, unlock and starting the car.