Ford Mustang key fob battery

Separate remote fob

1. This remote is its own fob, separate from the metal key, which makes it one of the easier ones to open.
2. Turn it over: some older fobs use one small screw, newer ones just clip. Pry at the seam once any screw is out.
3. Lift the old coin cell out and press the new one in with matching orientation.
4. Reassemble and test from a short distance.

This key takes two CR2016 cells. Change both at the same time and stack them the way the old pair sat; mixing a fresh cell with a tired one shortens the life of the new one.

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.

Key with remote in the head

1. This type has the buttons built into the key head. The cell is inside that head, between two clipped halves.
2. Many key heads split along the side seam. Start at the small notch and pry a little at a time.
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 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.

Smart key (push-button start)

1. Most push-button fobs hide a metal backup key. Press or slide its catch and draw the key out first.
2. The gap left by the metal key usually has a pry point. A slow twist with a thin flat tool (tape on the tip saves the plastic) opens the two halves.
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.

Ford intelligent access fobs usually have a release for the emergency key. The key blade itself fits the pry slot.

This key takes two CR2025 cells. Change both at the same time and stack them the way the old pair sat; mixing a fresh cell with a tired one shortens the life of the new one.

A CR2450 is 24.5 mm across and 5.0 mm thick, much fatter than a CR2032. A thinner cell will rattle and lose contact, so buy the exact size.