What frequency does keyless entry use?

Keyless entry relies on multiple radio-frequency bands, with a low-frequency wake-up signal around 125 kHz powering the fob and a higher-frequency data link in the megahertz or gigahertz range for the actual unlock signal. The exact frequencies vary by region and system, and some newer setups use Bluetooth or NFC for smartphone-based keys.

This article explains the main frequencies involved, how they are used in practice, regional variations, and how newer digital keys fit into the landscape.

Key frequencies and how they are used

Keyless-entry systems typically use a combination of bands to perform different tasks. Here are the primary frequencies you’ll encounter and what they do:

• Low-frequency wake-up/power signal: around 125 kHz (often 125–135 kHz) to power the passive transponder in the key fob so it can respond when in range.


• High-frequency data link for remote commands: commonly in the UHF range, with typical bands including:
  
  
  
  • 315 MHz in the United States and parts of Canada
  
  
  • 433.92 MHz in Europe and many other regions
  
  
  • 868/915 MHz in various regional implementations for newer or different systems
  
  
  
  


• Alternative or supplementary links: some systems use 2.4 GHz (Wi‑Fi/BLE/DIY remotes) for certain digital-key implementations, and a few newer designs incorporate NFC or UWB in specific applications.

In practice, a given vehicle may rely on one or several of these bands depending on the model, market, and generation of the keyless system. The low-frequency wake-up is separate from the data-carrying link, and the latter is what carries the unlock, start, or proximity commands.

Regional patterns and newer approaches

Different regions regulate and standardize keyless systems in distinct ways, and automakers adapt to these rules while pursuing stronger security. The following patterns capture common realities today:

• North America: many car remotes use 315 MHz for the unlock/start signal, alongside the 125 kHz wake-up channel for passive keys.


• Europe and parts of Asia: 433.92 MHz is widely used for remote commands, with 868 MHz also appearing in some regional implementations.


• United States and other markets: 902–928 MHz bands are used for some newer or specialized key systems, sometimes alongside 315 MHz.


• Emerging digital keys: smartphones and dedicated fobs increasingly rely on Bluetooth Low Energy (BLE) at around 2.4 GHz, and some systems experiment with Ultra-Wideband (UWB) for more precise proximity sensing. Near-field communication (NFC) is also used in some contexts, particularly for entry with smartphones or wearables in a close-range, secure manner.

The shift toward digital keys reflects regulatory considerations, security enhancements (like rolling codes and mutual authentication), and consumer demand for smartphone-based access. As a result, the exact frequencies a given system uses can change with new releases or regional variants.

Security considerations and regulatory context

Regulatory bodies such as the FCC in the United States and ETSI in Europe govern the allocations and usage of these bands. Manufacturers implement security measures—such as rolling codes, challenge-response authentication, and encrypted transmissions—to mitigate replay attacks and eavesdropping. When newer technologies like BLE or UWB are involved, they bring stronger proximity verification and anti-spoofing features, but also require careful implementation to protect user privacy and prevent unauthorized access.

Smartphones, digital keys, and the road ahead

Digital-key ecosystems rely heavily on BLE and sometimes NFC or UWB, enabling users to unlock and start vehicles with smartphones or smartwatches. These systems often combine the traditional RF key signals with secure cloud-based credentials and device-level security to improve convenience and security. Manufacturers continue to refine these approaches to balance reliability, battery life, and privacy.

Summary: Keyless entry uses multiple frequencies, most notably a low-frequency wake-up signal around 125 kHz and a high-frequency data link in the 315–433.92 MHz range depending on region, with newer systems also embracing 2.4 GHz Bluetooth, NFC, and UWB for digital keys. The exact setup depends on the vehicle, market, and technology generation, all within a framework governed by regional regulations and evolving security standards.

What signals do key fobs emit?

A key fob communicates with a receiver or a central system, most commonly a vehicle's or a building's access control system, using radio frequency identification (RFID) and rolling code technology. The fob sends a unique, encrypted signal to the receiver, which then authenticates the code to perform an action, such as unlocking doors or starting a car. 
Key functions and technology

• RFID technology: Key fobs use RFID to store and transmit a unique identifier, similar to an electronic barcode. This allows the receiver to identify the fob. 
• Radio frequency: The fob sends radio signals to a receiver in the car or door lock. This signal contains a unique, encrypted code. 
• Rolling code technology: To prevent signal interception, the code changes every time the fob is used. This makes it very difficult for a hacker to duplicate the signal. 
• Receiver and antennas: The vehicle's or building's system has a receiver to detect the signal. In a car, multiple antennas are used to determine the location of the key fob, ensuring it is inside or near the vehicle for certain functions like passive entry. 
• Multi-factor authentication: Some advanced key fobs can also be used as part of a multi-factor authentication process, often incorporating biometric data like a fingerprint, to provide an extra layer of security. 

What protocol does keyless entry use?

RFID technology
Explaining the Keyless Entry Tech in Cars
This is typically achieved through RFID technology or a similar wireless communication protocol. The key fob emits a unique signal or code that the vehicle's security system recognizes and verifies.

Do car keys use RFID or NFC?

For smart car keys, RFID has become the preferred technology due to its advantages in long-distance communication, low power consumption, high security, and cost-effectiveness. Although NFC has certain advantages in short-range communication, RFID is clearly the more competitive option in this application.

What radio frequency do key fobs use?

You can find a key fob's frequency by checking for a sticker on the fob, using a dedicated RF frequency tester, or using an SDR (Software-Defined Radio) with spectrum analysis software. Another method involves measuring the antenna's physical length, though this provides a less precise estimate. 
1. Look for a sticker on the fob 

• Open the key fob by separating the case, which may require removing a small screw or prying the halves apart. 
• Look for a sticker inside with the frequency listed, typically in MHz (e.g., 433433433 MHz or 315315315 MHz). 

This video shows how to open a key fob to find a sticker: 54sSecurity in mindYouTube · Apr 10, 2024
2. Use an RF frequency tester 

• Purchase a remote key fob frequency tester, which can be found on sites like Amazon or through auto parts stores.
• Place the key fob near the tester and press a button.
• The tester's display will show the frequency in MHz. 

You can watch this video to see how a key fob frequency tester works: 59sAnthonyJ350YouTube · Jan 23, 2018
3. Use a Software-Defined Radio (SDR) 

• Connect an SDR dongle to your computer.
• Install and run SDR software like GQRX or SDR#.
• Press a button on the key fob while the software is monitoring the radio spectrum.
• Look for a brief spike or jump in the signal to find the frequency. You may need to manually scan up or down by a few megahertz to find the signal. 

This video demonstrates how to use SDR to find a key fob's frequency: 56sNoisy HackerYouTube · Apr 18, 2021
4. Measure the antenna (Less precise) 

• Disassemble the fob to expose the antenna, which is often a thin, flexible wire or a printed circuit on the inside. 
• Measure the total length of the antenna wire or trace, accounting for any bends or curves. 
• Use online calculators and formulas that relate antenna length to frequency (typically for a quarter-wave or half-wave antenna) to get an approximate frequency.