How TPMS Sensors Communicate With Cars

Tire Pressure Monitoring System (TPMS) sensors in most modern cars communicate via low-power radio, transmitting pressure and temperature data from each wheel to a receiver in the vehicle—typically using 315 MHz or 433 MHz UHF signals, and, in some newer models, Bluetooth Low Energy (BLE). Indirect systems don’t use wheel-mounted radios at all; instead, they infer pressure from wheel-speed data already flowing on the car’s network. Together, these approaches keep drivers informed about underinflated tires and sudden air loss, meeting safety mandates in markets such as the U.S. and the EU.

Two Ways Cars Monitor Tire Pressure

Direct TPMS: Sensors That Broadcast From the Wheel

Direct TPMS places a battery-powered sensor inside each tire—usually integrated with the valve stem or strapped to the rim. Each sensor measures pressure and temperature and periodically broadcasts a short digital packet over radio to the car. The vehicle’s receiver picks up these packets, authenticates the sender by a unique ID, and forwards the readings to the instrument cluster and other control units. Many sensors also report battery status and basic diagnostics, and they transmit more frequently if they detect rapid pressure loss.

Indirect TPMS: No Radios, Just Math

Indirect TPMS relies on existing wheel-speed sensors from the ABS/ESC system. By comparing rotational speeds and vibration signatures across wheels, the vehicle estimates when a tire’s rolling radius has shrunk due to underinflation. There are no wireless transmissions from the wheels; all communication remains on the vehicle network. Indirect systems tend to be simpler and lighter, but they can be less precise and typically require recalibration after tire changes.

What’s Actually Transmitted

The following list outlines the core data fields found in a typical direct TPMS radio frame, which allow the car to identify the sensor, interpret pressure and temperature, and detect any urgent conditions.

• Unique sensor ID (to match each wheel’s sensor to the vehicle)
• Tire pressure (usually in steps of 0.1–1.0 psi/bar)
• Tire temperature (for pressure compensation and diagnostics)
• Status flags (e.g., low pressure, rapid deflation, sensor fault)
• Battery state and sensor health indicators
• Optional extra fields (e.g., motion state, sequence counters, protocol version)

Together, these fields let the car display accurate readings, trigger warnings promptly, and manage sensor pairing and maintenance workflows.

Frequencies, Protocols, and Emerging Bluetooth

Most direct TPMS sensors use unlicensed industrial, scientific, and medical (ISM) radio bands and simple, low-data-rate modulation to conserve battery life while ensuring robust range through the wheel well and vehicle bodywork. Regulations vary by region, so automakers select bands accordingly.

• 315 MHz UHF: Common in North America and parts of Asia for legacy and many current vehicles
• 433 MHz UHF: Widely used in Europe and also common globally, including many North American models
• 2.4 GHz Bluetooth Low Energy (BLE): Emerging in newer platforms and some EVs; enables encrypted links and easier over-the-air diagnostics

These radios typically use short bursts with ASK/FSK modulation under regional rules (e.g., FCC Part 15 in the U.S., ETSI EN 300 220 in Europe), with communication formats often aligned with industry guidelines such as SAE J2657 and OEM-specific protocols. BLE-based TPMS applies standard Bluetooth security features and can integrate more readily with modern vehicle electronics.

When and How Often Sensors Transmit

Because sensors run on tiny batteries, they transmit sparingly and intelligently. The timing is governed by motion detection and vehicle state, and it accelerates when safety demands it.

• Vehicle moving: Periodic broadcasts, typically every 15–60 seconds depending on speed and OEM strategy
• Vehicle stationary: Infrequent “keep-alive” updates or none at all to save power
• Rapid pressure loss: Immediate, higher-frequency bursts to alert the driver quickly
• Service/learn mode: Short-range activation via 125 kHz low-frequency (LF) triggers near each wheel to wake and identify sensors during maintenance

This duty cycle balances battery life—often 5–10 years—with the need for timely warnings when a tire loses air.

How the Car Knows Which Wheel Is Which

Beyond receiving data, the vehicle has to map each sensor ID to a specific corner (front-left, front-right, etc.). Automakers use several strategies to localize each sensor.

• LF initiators at each wheel well: A 125 kHz pulse wakes the nearest sensor, allowing precise wheel assignment
• Signal-strength and rotation correlation: The car infers position by RF strength plus patterns in sensor timing versus wheel rotation
• Manual learn via tool: A service device triggers each sensor in sequence while the car records their positions

These methods help maintain accurate per-wheel displays after tire rotations, wheel swaps, or sensor replacements.

Pairing Sensors and Relearn Procedures

New sensors must be introduced to the vehicle so their unique IDs are recognized. Depending on the model, this can be automatic or require explicit steps.

• Auto-learn while driving: The car listens for new IDs and assigns them after a drive cycle
• OBD-II service tool: A scan tool programs sensor IDs directly into the TPMS/BCM module
• LF-trigger sequence: A handheld activator pings sensors in a specified order while the car records them
• Owner-initiated calibration (indirect TPMS): A dashboard command resets the baseline after tire changes

Following the correct relearn process ensures the dashboard shows the right pressures and avoids spurious warnings.

From the Antenna to the Dashboard

RF antennas—sometimes one central unit, sometimes near each wheel—feed a TPMS receiver. Decoded data travels over the in-vehicle network (often CAN) to body and chassis control modules and the instrument cluster. The logic compares readings with thresholds set by regulations and the vehicle manufacturer; if pressure drops below limits (e.g., about 25% under recommended levels in U.S. rules), the warning lamp and messages appear.

Security, Interference, and Reliability

While TPMS transmissions are low-power and short, they share crowded spectrum and must be resilient. Newer designs also address security as cars become more connected.

• Interference and jamming: UHF links can be disrupted by noise; systems retry transmissions and use robust modulation
• Spoofing concerns: Early protocols had minimal authentication; modern and BLE-based systems add identifiers, counters, and encryption
• Battery constraints: Sensors conserve power aggressively; harsh temperatures or frequent transmissions can shorten life
• Fail-safes: If data is missing or implausible, the vehicle warns the driver rather than guessing

These measures aim to keep warnings dependable while minimizing false alerts and preserving sensor longevity.

Aftermarket and Heavy-Duty Variations

Aftermarket TPMS kits often use 433 MHz valve-cap sensors that talk to a plug-in receiver or BLE sensors that pair with a smartphone app. Commercial trucks and RVs may use external banded sensors or internal units, with communication principles similar to passenger cars but tailored for larger tires, longer ranges, and additional telemetry.

Bottom Line

Most TPMS sensors communicate by broadcasting low-power digital packets from each wheel over UHF radio, with BLE now appearing in newer platforms; the car’s receiver maps those IDs to wheel positions and relays pressure and temperature data over its internal network to trigger alerts. Indirect systems skip the radio entirely, estimating pressure from wheel-speed behavior. Both approaches serve the same goal: warning drivers quickly and reliably when tire pressure isn’t safe.

How are TPMS sensors programmed?

TPMS sensors are programmed using a TPMS scan tool to copy the unique ID of old sensors to new ones (cloning), program new IDs for aftermarket sensors, or configure a universal sensor for a specific vehicle before installation. After programming, a “relearn” procedure is necessary, which uses the same scan tool to make the vehicle’s computer recognize the new sensor’s data and location, often requiring a short drive or a specific tool function to complete the process. 
1. Understand Sensor Types 

• OEM (Original Equipment Manufacturer) sensors: Opens in new tabCome pre-programmed for a specific vehicle and do not need a separate programming step. 
• Programmable/Universal sensors: Opens in new tabBlank initially and require programming for the vehicle’s make, model, and year. 
• Pre-programmed/Ready sensors: Opens in new tabCome pre-loaded with a range of protocols and can often skip the programming step. 

2. Programming the Sensor

• Cloning: Opens in new tabThis method copies the unique ID from an old, functional sensor and writes it to the new sensor. This is useful if the old sensors are dead, as their IDs are stored in the car’s computer and can be retrieved. 
• Direct Programming: Opens in new tabA TPMS tool is used to input new, unique sensor IDs directly into the new sensor, which are then programmed into the vehicle’s computer. 

This video demonstrates how to program TPMS sensors by cloning, which copies the ID from an old sensor to a new one: 59sDIY DanYouTube · Sep 5, 2022
3. The Role of the TPMS Tool

• A specialized TPMS scan tool is essential to perform the programming. 
• The tool connects to the vehicle’s OBD-II port to retrieve or write sensor information to the car’s computer. 
• It is used to “wake up” or trigger the sensors to gather data. 

4. The “Relearn” Procedure 

• Crucial Step: After programming and installing the sensor, the vehicle’s computer needs to register it. 
• How It Works: The TPMS tool guides you through a relearn procedure to update the vehicle’s system with the new sensor’s ID and location. 
• Methods: Some vehicles offer automatic relearning after a short drive, while others require using a TPMS tool to trigger and register each sensor individually. 

How do TPMS sensors communicate with the module?

Tire pressure sensors send signals using tiny radio transmitters embedded within the tire. These TPMS sensors constantly monitor the air pressure inside the tire, and if it drops too far, they send a radio signal with the pressure data to your vehicle’s onboard computer.

How often do TPMS sensors send a signal?

TPMS sensors generally transmit data every 30-120 seconds when the vehicle is in motion and may transmit less frequently when parked, with some systems sending a signal immediately upon detecting a sudden pressure change. The exact transmission rate varies by vehicle manufacturer and system type, but a sudden pressure loss will always trigger an immediate transmission regardless of the sensor’s normal mode. 
Factors influencing transmission frequency: 

• Vehicle motion: When a wheel starts to roll, accelerometers in the sensor activate it to broadcast at regular intervals (rolling mode).
• Parked mode: While stationary, sensors may transmit less frequently or only in response to a significant pressure change, a behavior designed to conserve battery life.
• Sudden pressure loss: If a sensor detects a rapid drop in tire pressure, it will immediately send a signal, even if the vehicle is stationary.
• Manufacturer settings: Each manufacturer programs the sensor’s behavior, including its transmission interval, to meet the needs of their vehicle systems.

How the signal works:

• Low-frequency activation: Opens in new tabA low-frequency (LF) signal from a TPMS tool is often used to “wake up” or activate the sensor when needed for service or diagnosis. 
• UHF broadcast: Opens in new tabOnce activated or in rolling mode, the sensor transmits data via a UHF radio signal to the vehicle’s onboard computer. 
• Data included: Opens in new tabThe transmitted signal contains the sensor’s unique ID, the tire pressure, and sometimes the tire temperature. 

How do TPMS sensors communicate with the car?

A TPMS sensor transmits a very-low power signal that goes in all directions. The waves are absorbed and reflected off the vehicle and environment. The antenna could be on the windshield, in the wheel well or in other locations.