What Is a Key Fob?

Honolulu Locksmith
April 16, 2024

In early automotive history, metal keys were the only way drivers could enter and start their cars. A better alternative was innovated around the turn of the 21st century. That's when the first key fobs appeared on the market.

A key fob (fob) is a small battery-operated security device that is used to perform certain functions for vehicles. Fobs can be used to lock and unlock vehicle doors, pop open trunks, and in some cases, start ignition systems. Note: Most fobs are no bigger that a small domino.

It is worth also noting that fobs were originally defined as keychains or small pockets for carrying things like pocket watches.

How Does a Key Fob Work?

When pressed, a car key fob will send a random radio signal to the appropriate car's onboard computer system. The computer system has been programmed to read the radio signal and perform the appropriate function as indicated on the fob. Yes, the fob has several buttons, one for each function it can initiate. As indicated above, the most common functions a fob can perform is locking/unlocking doors and trunks and starting ignition systems.

In most cases, a rolling code technology is used to select a random scrambled radio signal. These signals can only be unscrambled by the applicable car onboard computer. With this technology, a particular code can only be generated and accepted once.

Being that this technology is very specific between one car key fob and one computer, it provides a high level of security against unwanted and unauthorized car access.

Car Key Fob Device

What Kind of Issues Can Happen To a Key Fob Device?

If a key fob is not working, there is a small chance the issue involves the car's onboard computer system. However, that's seldom the case. If that did happen, it would likely be evident by the fact other computerized car functions would also fail.

The more likely reason a key fob is not working is the device itself. Anything that has moving parts will always be subject to malfunctioning or breaking. In the case of a car fob device, there are several common problems that might occur. That would include:

  • The random code generation process fails
  • One of the buttons ceases to work
  • The outer-casing of the device breaks
  • The device gets lost or stolen
  • The device battery runs out of juice

Our Key Fob Services at Honolulu Locksmith in Honolulu, Hawaii

Honolulu Locksmith is a full service locksmith service that operates in parts of Hawaii. As a local locksmith to the island of Oahu, we encounter more than our fair share of issues related to fobs or keyless remote devices. That's not a problem for us because our special team of locksmith technicians are well-versed on how to resolve such issues quickly and efficiently. Here is a list of locksmith services we provide related to keyless remote devices:

Person holding a car key fob


Assuming your vehicle was manufactured in the last 20-25 years, there is an excellent chance you are relying on a car key fob to perform certain automotive function. There is also an excellent chance that you will eventually encounter a problem with your device.

Based on the information we provided above, you should now have a basic overview of how fob devices function. You can use this information to help you determine when something is not working as it should. When such issues arise, the best and fastest way to resolve fob device-related issues is to contact a top-rated locksmith service like Honolulu Locksmith. Our prices are affordable and our services are guaranteed.

Frequently Asked Questions

If I have a fob battery issue, can I fix it myself?

If your device has a removable cover, you can probably handle this key fob repair yourself after you find the right battery. However, some devices require the use of a special tool to remove the cover. In such cases, you would need to call the dealership (expensive) or a reliable local locksmith.

How long does it take to replace a fob device?

In most instances, our mobile locksmith units will be stocked with a device that's suitable for your vehicle. Sometimes, we might need a little time to locate an appropriate device, which might take an hour. Once our locksmith has the appropriate device, they can usually complete the programming process in 15-30 minutes.

Is there a difference between a fob device and a transponder key?

Yes. The most obvious difference between these two keyless entry options is a fob may or may not be able to start an ignition. Conversely, a transponder key system works off of a computer chip located in the key casing. The ignition will only start if the transponder key's chip is functional.

Is anything special required to replace a lost fob?

Yes. We would need three (3) things: proof of your identity, documentation that shows you have legal access to the vehicle, and clear access to the car's VIN #.