What Is A Car Smart key?: Compare With Keyless! Usage And Notes

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Smart keys have been introduced in many cars, but many people may be “unsure” of the detailed mechanisms and features. In particular, it may be difficult to understand the difference between a smart key and a keyless key that can be operated remotely.

The difference between a smart key and a keyless key is simply summarized as “the ability to operate the car without holding the key in your hand.

In this article, we will introduce how the smart key works, how to use it, and points to note, including the differences from a more detailed keyless system.

In the latter half of the article, we also explain the precautions to be taken when using a smart key, so please refer to this article as a reference for theft prevention as well.

What Is A Smart Key?

A smart key is a key for a car that does not require a keyhole and can be operated by simply approaching or touching the car.

The function of a smart key is called a “smart entry system,” and it can be used to lock and unlock doors, start and stop the engine, and open and close doors automatically.

Although detailed operations vary from car to car, as long as the smart key is held by the car, it can be operated without taking it out of a bag or pocket.

There are various types of smart keys for locking and unlocking, such as the type that presses a button near the door handle, or the type that responds to the LF antenna built into the door handle or a touch sensor.

How Smart Keys Work

The smart entry system reacts when it receives weak radio waves emitted by the car and the smart key from each other. The car can be unlocked and locked without removing the key from the car because the radio waves are exchanged with the car in the following way.

  1. The smart key enters within a certain distance from the car.
  2. The car transmits a radio wave
  3. The smart key receives a radio wave from the car
  4. The smart key transmits a signal to the car
  5. The car receives the radio wave from the smart key
  6. Car keys can be unlocked and locked

In addition to locking and unlocking the keys, starting and stopping the engine and opening and closing the doors can also be handled in the same way. The car is equipped with devices such as an “in-car LF antenna” and an “in-car RF receiver,” each of which emits different frequencies.

  • In-vehicle LF antenna: Abbreviation for Low Frequency, using a frequency band of around 125 kHz.
  • In-vehicle RF receiver: Abbreviation for Radio Frequency, using a frequency band of around 312.125 MHz.

Because these radio waves are weak, they generally do not respond unless the car and the smart key are within a certain range (within an approximate radius of 0.5 to 1 meter) of each other.

Even if there is a person with a smart key, the car will not react if the person is far away from the car, so the risk of a stranger operating the car is low.

Incidentally, the smart key has a built-in mechanical key. A mechanical key refers to a conventional metal key, which is also called an emergency key.

Even in an emergency when the smart key does not respond properly, the built-in mechanical key can be inserted to operate the engine and doors.

History Of Smart Key

The smart key (smart entry system) has been equipped mainly in luxury cars for more than 10 years since its birth.

The first car equipped with a smart key was the Chevrolet Corvette launched in the 1993s. At that time, it was not called a smart key, but rather the Passive Keyless Entry System.

In 1998, the system was installed in the Mercedes-Benz S-Class under the name Keyless Go, and from 2000 onward, it gradually became standard equipment in light vehicles as well.

The mechanism and format of smart keys have evolved along with technological developments, and some cars now have keyholes on the door knobs that are not visible from the outside, both to prevent theft and for design purposes.

Different Manufacturers Call Smart Keys By Different Names

As in the past, the name of the smart key differs from manufacturer to manufacturer, and you will see familiar words in TV commercials.

List Of Names Of Japanese Car Manufacturers

Maker System name
Toyota Smart Entry & Start System
Nissan Intelligent Key System
Honda Honda Smart Key System
Suzuki Keyless Start System
Subaru Keyless Access System
Mitsubishi Keyless Operation System
Daihatsu Keyfree System
Mazda Advanced Keyless Entry & Start System

List Of Names Of Foreign Car Manufacturers

Maker System name
Volkswagen Smart Entry & Start System
Audi Advanced Key System
BMW (MINI) Comfort Access
Mercedes-Benz Keyless Go & Hands-free Access

What Is The Difference Between A Smart Key And A Keyless Key?

There are two differences between smart keys and keyless keys: when locking/unlocking doors and when starting/stopping the engine. Keyless is called “keyless entry system” and was the mainstream key in the generation before the smart key.

Differences When Unlocking And Locking Doors

Keyless key: unlocked and locked by pressing a button on the key.
Smart key: Can be used to open and lock the door by approaching or touching the door.

Can be used to open and lock the door by approaching or touching it, and can also be used to automatically lock the door after a certain period of time if you leave the car.

Differences When Starting/Stopping The Engine

Keyless key: Key must be inserted into the keyhole (key cylinder) and turned.
Smart key: No need to insert the key into the keyhole. As long as you have the key inside the car, you can start and stop the engine by operating the brake and pushing in the engine switch.

Smart keys are also sometimes confused with other types of keys, such as “remote control keys” and “immobilizer keys.” Smart keys can be treated as remote control keys, but there are also smart keys with built-in anti-theft function immobilizers.

Whether or not a key is a smart key is determined by whether or not it has a built-in system (smart entry system) that allows the driver to operate the car without having to remove the key.

Advantages And Disadvantages Of Smart Keys

Although smart keys can operate a car remotely and without touching the key itself, there are many attractive aspects of smart keys, but there are also some disadvantages that are often overlooked.

Advantages Of Smart Keys

  • No need to take the key in and out of the car, thus preventing loss.
  • Easy to open and lock doors even when your hands are full.
  • The engine operation can be simplified by using a switch or a dial.
  • Prevention of picking through the keyhole.

Placing keys in pockets or bags reduces the number of times they need to be taken out, and thus inhibits behavior that can cause them to be lost.

Even if the location of the key is uncertain, the car will respond within a certain range, so if the key can be opened and locked, it will be a good sign that the key is always in the vicinity.

In addition, smart keys do not require the user to “look for the key” or “insert the key into the keyhole.

In addition to simplifying the process of starting the engine, the appearance of vehicles without keyholes in the door handles has also made it possible to realize the benefit of preventing damage from pickpocketing.

Disadvantages Of Smart Keys

  • The built-in battery has a short lifespan of 1-2 years (can be unlocked with a mechanical key).
  • Key lock-in can easily occur.
  • There is no 100% operation guarantee.
  • There is a possibility of being a victim of a relay attack.

Since smart keys are powered by built-in batteries, they must be used with concern for battery life. The lifespan is surprisingly short, and most automobile manufacturers recommend replacing batteries at one- to two-year intervals.

Although manufacturers often set their recommended times at a generous number of years to ensure safety, it is necessary to replace batteries regularly to avoid panic caused by dead batteries on the road.

In addition, with the increase in the amount of time that people are not aware of their keys, there are many problems with keys being locked in the car.

Since about 154,742 cases of key lock-in problems occur annually as reported by JAF road service, it is necessary to be very careful in handling keys.

Furthermore, although they are resistant to damage from physical picking, they are not a perfect security measure, as they can be stolen by a method called relay attack (radio wave interception).

It is also important to remember that smart keys are electronic devices. There is a risk that the smart key may malfunction due to shock or another electromagnetic wave.

Smart Key Usage

This section explains how to use the smart key according to two patterns: when the smart key is in normal use and when the batteries are dead.

When The Smart Key Is In Normal Use

1. Approach the car with the smart key.
2. Open the door and get in after confirming the operation sound and the lamp flashes.
3. Confirm that the smart key is in the car and that the gear is in parking
4. Step on the brake and operate the engine switch (or dial)
5. Upon arrival, put the gear in parking and operate the switch (or dial) on the engine to stop
6. After stopping the engine, exit the car with the smart key
7. Leave the car and check for automatic locking, operation sound and lamp flashing
*When exiting the car, the door can also be locked by touching the door handle in the same way as when opening the door.

If The Battery In The Smart Key Is Dead

1. Remove the fixture from inside the smart key and take out the mechanical key.
2. Insert the key into the keyhole located around the door handle on the driver’s side to unlock the car.
3. Confirm that the gear is in parking.
4. Operate the engine switch (or dial)
5. While stepping on the brake, place the manufacturer’s emblem on the switch (or dial)
6. Operate the engine switch (or dial) again after confirming that the switch or indicator is blinking
*When the battery runs out, the method of dealing with the situation differs depending on the manufacturer.
*The above operation method applies to “Honda vehicles”.

Avoid Risks In Advance! What To Look Out For When Using A Smart Key

When using a smart key, you should be aware of four precautions.
Please check them to prevent loss or problems during use.

The Driver Must Carry The Smart Key With Him Or Her

If the person with the key leaves the car after starting the engine, the engine that was running will stop and a warning alarm will sound at the same time. Once the engine is stopped, it cannot be restarted until the smart key is returned to the car and recognized.

Nevertheless, if the keys are left in the car after the engine has started, there is a risk that a stranger may get into and out of the car, so care should be taken to ensure that the smart key is in the possession of the driver only.

There is also a risk that if the key owner leaves the car and the automatic lock is triggered by the key owner leaving someone in the car, the car will vibrate and the anti-theft alarm will go off.

Preventing The Loss Of Smart Keys

If you lose your smart key, you can ask the store where you purchased the car to make a key for you. In most cases, this can be done on the same day, but the average cost is about 20,000 yen.

Similarly, if you are concerned about losing your smart key and wish to have it duplicated, you will need to spend at least 10,000 yen.

Since neither of these options is inexpensive, take great care not to lose your smart key.

If you would like to duplicate a spare smart key in case of emergency, you can find a vendor who can handle the job through GooNet Pit. You can quickly find a compatible vendor near you.

Be Prepared For Relay Attack Damage

As mentioned briefly earlier, the widespread use of smart keys has led to a number of thefts known as “relay attacks,” in which the radio waves from the car and the smart key are read to open the door.

To prevent theft by relay attack, it is necessary to devise ways to prevent a third party from picking up the transmission and reception of the smart key and the car.

Radio wave blocking pouches are available as an anti-theft item to keep the smart key in, so it is a good idea to have one ready in case of an emergency.

Consideration For Pacemakers

Smart entry systems that use weak radio waves have the risk of adversely affecting pacemakers.

According to a survey by the National Institute of Medical Devices and Computing, the risk of interference between the two is low if the antennas of the smart key system are at least 22 cm apart.

There are several other matters to be aware of between pacemakers and smart entry systems, so regardless of whether you drive a car with or without a smart entry system, check the details beforehand if applicable.


A smart key is an electronic key equipped with a smart entry system that can “lock/unlock/open/close the doors” and “start/stop the engine” without touching the key and car.

Although often confused with keyless keys or remote control keys, only smart keys can be operated by radio waves without having to hold the key.

Despite the convenience of the smart key, there are many problems that occur after switching to a car equipped with a smart key. If you own or plan to purchase a car equipped with a smart key, be very careful when handling the key.