Toyota 86 key fob battery

Key with remote in the head

1. The remote electronics sit in the plastic head of the key itself, so there is no separate fob to open.
2. Find the seam around the head. Twist a coin or small flat screwdriver in the notch at the blade end or side until the halves part.
3. The coin cell is usually under or on the back of a small board. Keep the rubber button pad in place while you swap the cell.
4. Press the head together until it clicks and test the buttons. The transponder chip that lets the car start is separate from the battery, so starting should not change.

A CR2016 is 20 mm across and 1.6 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.

Smart key (push-button start)

1. Find the small release on the edge or back of the fob and hold it while you pull out the metal emergency key.
2. Use the slot where the metal key sat. Twist, do not lever hard, and work along the seam until the halves separate.
3. Pop the old battery out with a toothpick or plastic pick, not a metal blade, and seat the new one with the + side matching the old one.
4. Close the case until it clicks all the way round, put the metal key back, then try the buttons and a push-button start.

On most Toyota smart keys the metal key slides out after you press a small release, and the case opens at the slot it leaves behind.

A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.