How To Replace A Key Fob Battery
A weak key battery reduces remote range and, on keyless cars, can stop the car recognising the key. Replacing it usually takes a few minutes.
DifficultyEasy
TimeAbout 5 minutes
AreaBattery and electrical
What you need
- The correct coin cellThe type is printed on the old battery, for example CR2032.
- Small flat toolA plastic opener avoids scratches.
Step by step
- Remove the mechanical keyMany fobs have a hidden emergency key that also opens the case.
- Open the case carefullyUse the notch provided.
- Note the polarityUsually the + side faces up.
- Swap the batteryAvoid touching the contacts with greasy fingers.
- Close and testLock and unlock the car, and start it.
When to go to a workshop
If the key still does not work, it may need reprogramming or repair. A flashing immobiliser light after a battery change can mean the key is not recognised.
Questions about How To Replace A Key Fob Battery
Can I still start the car with a flat fob?
Many cars have a backup position where the key is read at close range; see the manual.
Does the key need reprogramming?
Usually not after a simple battery swap.