A proximity key is a small fob that allows for a keyless entry and ignition system. First introduced by Mercedes-Benz in 1998, keyless entry vehicles are taking a larger market share every year and showing no signs of slowing down. The fob communicates via radio waves with your car to lock and unlock doors and start the engine when within the acceptable range. Proximity keys are known by a variety of names, such as:

  • Intelligent Key
  • Keyless Access
  • Keyless Entry
  • Keyless Go
  • Push Button Start
  • Push-to-Start
  • Smart Key

The smart key allows the driver to keep the key fob in a pocket or purse when locking, unlocking, and starting the vehicle. The key is identified via one of several antennae in the car’s bodywork and a radio pulse generator in the key housing. Vehicles with a smart key system also have a mechanical key back-up, usually in the form of a spare key blade supplied with the vehicle. Generally, the key hole is hidden behind a cover plate for aesthetics.

A Mercedes-Benz convertible parked near some grass.

How do proximity keys work?

Vehicles with a smart key system can disengage the immobilizer and activate the ignition without inserting a key in the ignition, provided that the driver has the key inside the car. On most vehicles, this is done by pressing a starter button or twisting an ignition switch. There are also vehicles which have an ignition slot for the proximity key.

Many people don’t realize that their proximity keys contain an emergency key blade within the remote that may be used to open, close, and start your car. This back-up option is necessary in the event that the battery in the smart key becomes depleted, although some vehicles can be started via the use of a transponder chip inside the smart key that doesn’t need batteries to work. There is usually a designated slot or area in which the key must be held in order for the transponder to be detected and start the engine.

A push-to-start button on a vehicle dashboard.

Benefits of proximity keys

There are several benefits to using proximity keys and keyless entry systems. For one, they’re more convenient than traditional keys,  making it easier to get into your car if you have your hands full. They can also improve your car’s security. Proximity keys often have built-in security features that make it more difficult for thieves to steal your car. 

If you’re considering adding a proximity key or keyless entry system to your car, be sure to talk to your auto insurance provider. Some insurers offer discounts on premiums for cars with these features thanks to the improved vehicle security they provide.

An interior shot of a man driving a car at sunset.

Drawbacks of proximity keys

If you lose your proximity key or keyless entry fob, or if your battery dies unexpectedly, you’re out of luck. On many vehicles, there’s no way to start your car without it. That means you’ll have to call a tow truck or have someone else bring you a spare key. For this reason, we recommend that you duplicate your smart key so you or a trusted contact always have a backup on hand. 

Another downside is that these types of keys and systems can be expensive. If you lose your keyless entry fob, you’ll likely have to pay for a replacement from the dealership. And if your car’s proximity key system isn’t working properly, costs for repairs will be much higher than those on a more traditional ignition system. Luckily, Pop-A-Lock’s key replacement service will supply a new key at a lower cost than the dealership, so be sure to check with your local Pop-A-Lock branch to get a quote before you head to the dealer.

Proximity keys and keyless entry systems for cars are gaining in popularity. If you don’t already own a car with this feature, there’s a good chance you will in the future. It’s a good idea to familiarize yourself with the ins and outs of what they are and how they work. And, if you ever find yourself stuck outside your car when your proximity key malfunctions, be sure to contact our automotive services professionals to get you back on your way.