Match the cell before you open the fob
Confirm the code and quantity from the car key fob battery finder (or your owner’s manual) for your key style.
Prefer child-resistant coin-cell packaging when you can. Keep new and used cells away from children and pets.
Chemical burn hazard
Button and coin batteries can cause severe internal burns if swallowed. If you suspect a child has swallowed a battery, seek medical attention immediately.
Do not leave open fobs, loose cells, or packaging where toddlers can reach them.
Polarity and handling
Install with the polarity shown in the manual figure or on the tray. Many remotes need the + facing a specific direction — habit is not enough.
Avoid shorting the cell with metal tools. Don’t wipe dielectric grease off contacts unless the maker says to. Don’t force a thicker cell into a thinner compartment.
What this guide does not cover
We do not provide key programming, immobilizer reset, blade cutting, or shell replacement steps. If the remote still fails after a correct fresh cell, see a dealer or qualified locksmith — not a random YouTube “program your key” video as a first step.
Quick takeaway
Right code → right polarity → keep cells away from children. Programming is out of scope here.