Ford Focus key fob battery

Separate remote fob

1. The remote is a small standalone unit. You will not need to touch the ignition key at all.
2. Look for a screw on the back or a notch on the edge. Remove the screw if present, then twist a coin in the notch to split the case.
3. Swap the cell or cells, keeping the same side up as the old ones.
4. Snap the case shut and watch for the lights to flash when you press lock at the car.

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. 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.

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

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. The remote electronics sit in the plastic head of the key itself, so there is no separate fob to open.
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. Inside you may find a small circuit board in a tray. Lift the board out if the cell is underneath, swap the cell with the same side up, and refit the board.
4. Snap it closed and press each button. The car still starts with a dead remote battery on most of these keys, because the start chip needs no battery.

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.