A key fob that refuses to unlock the door on your vehicle can be really frustrating, and possibly even dangerous - especially if there is a small child or pet locked inside your vehicle. So here are some reasons why your remote key fob or smart fob isn't unlocking the door, and what you can do to resolve the problem.
If nothing happens when you press the unlock button on your remote or key fob, any of the following could be causing your problem:
The battery inside your remote fob or smart key fob is dead or too low to send out a good signal. Open the fob and replace the battery.
The keyless entry system receiver(s) on your vehicle may not be picking up the signal from the key fob. Try holding the fob right next to the door handle when pressing the unlock button. If it unlocks the door, the problem may be a weak battery in the key fob, or a problem in the keyless entry antenna or wiring.
The key fob itself could be defective or have a bad unlock button. Try the lock button, trunk release button or panic button. If the other buttons work, the problem is a bad unlock button. You will need a new key fob (which will have to be programmed to your vehicle). If none of the other buttons work, and you have tried a new battery in the fob, the fob may be bad, or the fault may be in the keyless entry antenna or wiring.
Your key fob has lost its entry code. Many vehicles use a rolling code that changes each time you use the fob to unlock or start your vehicle. If miscommunication has messed up the code in the fob, you may have to have it reprogrammed by a car dealer.
The power door locks may be defective. A fault in the wiring or control circuitry, or even a blown fuse may be preventing the power door locks from unlocking. This will require further diagnosis of the electrical system to determine the fault.
Your car battery is extremely low or dead. This may require a jump start or replacing the car battery before the power doors will unlock. Of course you probably won't be able to open the hood until you can get inside the vehicle by other means.
If nothing happens when you press the unlock button on your remote entry key fob, and you have tried a replacing the battery inside the fob, your either have a bad fob or a fault in the keyless entry system or power door locks.
If you have a spare remote entry key fob or smart fob, try using that fob to unlock the door. If it works, you need to replace the other key fob with a new one. If the spare doesn't work, the fault is in the car, not the fob. This may require towing the vehicle to a service facility or car dealer for diagnosis and repair.
If getting inside your car is essential right now, check your fob for a hidden key inside. Most vehicles that have a keyless entry system and Smart fob (Start button instead of an ignition switch and conventional key) have an emergency door key hidden inside the fob. There is usually a small release catch or button on the back fo the fob that allows you to pull the key out of the fob. You can then use the key to unlock the door.
If the door handle does not have an obvious keyhole to accept the emergency key or a valet key, there is usually a "hidden" key slot under the handle trim near the edge of the door. You may see a small slot in the bottom of the handle trim. Insert the key into this slot to pry the trim cover off. Some covers slide up to remove, or to the right to remove. Once the cover is off, you should see the key slot for the emergency key to unlock the door.
If your fob has no hidden key inside, or you can't find the hidden emergency key slot to unlock the door, your next option would be to call a cop. They are fairly good at breaking into cars and unlocking doors. They will use a long thin tool called a Slim Jim to unlock your door. The tool is slid down into the door between the glass and door panel to catch and release the lock mechanism.
Finally, if all else fails, and no cop is available to help you get inside your vehicle, and you absolutely have to get inside by any means possible (say to rescue a small child or a pet that's trapped inside on a hot day), pick up a rock or something hard and smash out the driver's door window. Then reach inside an unlock the door.
Car thieves have figured out how to use electronic equipment that can ping your key fob for a code signal. The equipment has the same range as your key fob, which means it can hack your fob in your pocket or your home from up to 30 or 40 feet away. When your fob hears the fake signal, it sends back a coded reply to your vehicle. The thief records the signal, then uses it to open your doors. If the fob is also used to start the engine, the thief can do the same and steal your car!
The best way to "foil" would-be car thieves using this trick is to wrap your key fob in aluminum foil when your vehicle is parked. Or, keep your fob inside an enclosed metal container such as an Altoids can or old metal coffee can with a metal lid. The metal enclosure must completely surround the fob to block all radio waves so your fob cannot be hacked.