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How to Replace or Repair Your Car’s Key Fob

Lost or broken devices can be costly and leave you without a ride


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Most new cars today come with a key fob that allows drivers to enter the vehicle without putting a key in the door lock. Some even control a car’s ignition. But what happens when that fob gets lost or damaged?

The device can be expensive to replace, so some drivers are tempted to find a cheap option online instead of turning to a dealer or a reputable automotive locksmith. But experts recommend against going that route. For one thing, it might not work, but it can also leave drivers open to scammers.

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“When customers buy their own fobs after doing searches for makes and model years, they often don’t work,” says Max Wilson, formerly with the Locksmith Agency in Richmond, Virginia, that now operates as 1-800-UNLOCKS. A lot of fobs look exactly alike, but their radio frequencies are different.

A key fob is an electronic device that controls entry and perhaps ignition without having to use an actual key. The fob communicates with the vehicle using radio waves that align with the car’s locking mechanism. Most new cars come with two fobs, and they often have enhanced functions, such as the ability to start a car remotely or lower all the windows at once.

To do its job, an automobile fob radiates a unique, low-frequency signal to a receiver unit in the car. When the unit registers that the signal is correct, it allows the driver to use the fob to unlock doors, start the car’s engine or perform other tasks.

Car makes and models have different versions of these radio frequency numbers. That means the radio signals that connect the fob to the reader in the door of one 2023 Toyota Tundra, for example, may be different from those mated with other 2023 Toyota Tundras.

“Every single detail matters when you buy a new fob,” says Sam Wilson, Max’s brother, a second-generation locksmith and owner of 1-800-UNLOCKS. “Think of it this way: You can’t buy one traditional key and expect it to work on every car. It’s the same with fobs. There are a lot of variables.”

Save money: Check these 3 things first before replacing

Replacing automobile key fobs can be pricey. Costs can range from $50 to $400 per fob, and programming will be another $50 to $100.

1. Make sure the old fob really needs to be replaced before buying a new one. Start by checking and replacing the batteries. The device may need maintenance but not replacement.

2. Reprogram the remote, kind of like resetting your cellphone.

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3. Find out whether your insurance or car warranty covers the replacement of fobs or lost keys.

Because buying the proper key fob can be expensive, the best thing a vehicle owner can do is keep existing fobs in good shape. Place the devices in a secure location and make sure to protect them from water, which can do damage.

Beware of scammers and thieves

Faulty fobs can leave your car’s computer more vulnerable to hacking and even fail at such basic functions as shutting off the car’s engine. Thieves have been known to tap into the signal of a fob left near a front door, hack into the car and drive away.

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When you’re replacing or repairing your fob, do your homework if you’re considering an option besides the dealer. Some automotive locksmiths can replace and reprogram fobs, but going to a reputable locksmith is essential.

Verify all training and certification paperwork, and look at websites and online reviews.

Extra equipment can make for a lengthy replacement process. If your car features specialized equipment — such as a breathalyzer — replacing the fob may involve several steps. A locksmith will need a court order to remove the breathalyzer before reprogramming the fob.

Sam Wilson estimates it should cost $150 to $250 to have a locksmith come to you and reprogram an existing fob.

“If it is much higher or lower, price check it by calling other places,” he says. “A lot of the locksmith industry is filled with fraudulent practices. You want to find someone who won’t overcharge or do bait and switch. Ask questions.”

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close up of a gold car parked near the water during sunset

AARP Auto Buying Program Powered by TrueCar

Shop for a car with safety features you want. Buyers can get a free AARP Smart Driver course.

close up of a gold car parked near the water during sunset

Please Select Make

Please Enter ZIP Code

Please Select Make

Please Enter ZIP Code