Kia Optima key fob battery

Smart key (push-button start)

1. Start by freeing the hidden metal key: there is a latch or slide on the case, and the blade comes out once it moves.
2. Look inside the empty key slot for a notch. Put the tip of the metal key or a small flat screwdriver wrapped in tape there and twist gently until the shell splits.
3. Note which side of the old coin cell faces up (usually the side with the writing), lift it out with a plastic tool, and press the new one in the same way.
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.

Kia smart keys usually free the mechanical key with a button, and the case opens at the gap it leaves.

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.

Flip key

1. Swing the key blade open first. On most flip keys the cell lives in the body behind the hinge.
2. Find the seam or small slot on the body (often at the end away from the blade) and twist a coin or small flat screwdriver in it until the cover lifts.
3. Take out the old cell, noting which side faced you, and fit the new one the same way.
4. Clip the body closed, fold the blade, and test the buttons from a few steps away.

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.