Honda Ridgeline key fob battery

Key with remote in the head

1. Here the key blade and remote are one piece. You open the plastic head, not the blade.
2. Work a thin flat tool into the seam near the blade and twist; go round slowly if it does not open at once.
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. Close the head, check there is no gap, and try the buttons.

A CR1616 is 16 mm across and 1.6 mm thick. It is easy to confuse with the 20 mm CR20xx sizes, which will not fit.

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. Before you take the old cell out, look at its face. Put the new cell in with the same side showing, and avoid touching both faces at once.
4. Reassemble, refit the emergency key, and check that the car sees the fob when you press start.

Honda smart keys typically have a release lever for the built-in key. Twist a coin or the key tip in the slot it exposes to split the case.

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.