Making A Safe Choice For Your Home

Why Has Your Car's Key Fob Suddenly Given Up?

by Kristen Roberts

You press the button on your key fob, and your car door moves all spring upwards simultaneously, unlocking all the doors. It's as predictable and reliable as the sun rising each day—until one day, it doesn't work. What can cause the sudden failure of a key fob?

Battery Replacement

Hopefully the problem has the most obvious solution. Most key fobs take a small button cell battery, and the most commonly-used variety is the battery code CR2032, which is a lithium battery. Refer to your vehicle manual for the precise battery category for your specific fob. Change the battery and try to remotely unlock your vehicle again. 

Fob Repair

If changing the battery fails to correct the problem, the fob itself may be faulty. The fob can be dismantled to check that the buttons and the terminals inside (which are activated by pressing the buttons on the fob) are not jammed or dirty. It's easy to inadvertently damage the fob if you do this yourself, and while you can probably dismantle the fob, reassembling it to working order is another matter. It's best to take the fob to a car locksmith for a professional assessment.

Fob Replacement

Any wear and tear to a fob can be repaired, but it's generally simpler to replace the entire unit. A generic model of fob can be provided and programmed to operate with your vehicle. This is a faster (and perhaps less expensive) option than repairing the fob. However, there's the possibility that the new fob (which is in perfect working order) still fails to remotely unlock your vehicle.

Engine Control Unit

Once issues with the fob have been ruled out, you need to consider that there's an issue with the vehicle itself. A working fob sends the correct unlock signal to the vehicle's engine control unit (which is its onboard computer). The unit should then trigger the solenoids that control each door, causing the simultaneous unlocking of all doors. 

Wiring and Fuses

There may be a wiring issue or a blown fuse that is preventing the correct signal from being sent to the vehicle's solenoids. If you inspect the vehicle's fuse box, the blown fuse may even be visible. That at least sheds some light on the situation, but the remote unlocking of your vehicle can only be restored when the damaged component is replaced. Call a car locksmith for onsite service. 

You'd hope that a car that fails to unlock is nothing more than a dead battery in its fob, but if the process of elimination determines a more serious problem, you may need some help from a car locksmith. For more information, contact a car locksmith near you.