Mazda CX-7 key fob battery

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. 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. 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. Snap the halves back together, slide the metal key home, and press each button, then try the start button from the driver's seat.

Mazda advanced keys usually have a knob or button that frees the auxiliary key; the cover lifts once the key is out.

A CR2025 is 20 mm across and 2.5 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. Fold the blade out so it is out of the way, or keep it folded if your case opens from the side; the battery sits in the plastic body, not the blade.
2. Look along the edge for a notch. A coin turned in that notch usually separates the remote half from the blade half.
3. Lift the cell out with a plastic tool and press in the new one with the + side matching.
4. Close it up, check the blade still flips cleanly, and test the buttons at the car.

A CR1620 is 16 mm across and 2.0 mm thick. It is easy to confuse with the 20 mm CR20xx sizes, which will not fit.