TPMS: Types, Principles, & Care

TPMS Becomes Standard: Driven by the Emphasis on Driving Safety

With the continuous advancement of automotive safety technology, tire pressure monitoring systems (TPMS) have transitioned from an optional feature to mandatory standard equipment on new vehicles. This shift reflects the global emphasis on driving safety. According to statistics, approximately 30% of highway accidents are related to tire failure, and abnormal tire pressure (excessively high, low, or slow leaks) is the primary cause of tire failure.

As the core executive component of TPMS, tire pressure monitoring sensors act as "smart health checkers" for tires, capturing real-time tire pressure and temperature data and transmitting them wirelessly to the vehicle's central control system. If the data exceeds safety thresholds, the driver is immediately alerted with audible and visual alarms, mitigating risks like blowouts and skidding at the source and providing a critical defense against driving safety.

Technical Principle: Real-Time Data Collection and Intelligent Warning Logic

Technical principles: tire pressure monitoring sensors continuously collect real-time data from within the tire using built-in pressure and temperature sensors and wireless transmitters. Its operating logic is simple: when the vehicle is started, the sensor activates, collecting pressure and temperature information every 3-5 seconds. If the data is within the normal range (typically 2.2-2.5 bar and temperature not exceeding 80°C), it transmits the data to the central control system at a low frequency (every 30-60 seconds).

If it detects a sudden drop in tire pressure (such as a sudden leak), excessive tire pressure (such as from excessive heat exposure), or an abnormally high temperature, it immediately switches to a high-frequency transmission (every 1-2 seconds) and triggers an alarm in the central control system, ensuring the driver is immediately aware of potential hazards.

Type Comparison: Core Differences Between Internal and External Tire Pressure Monitoring Sensors
Currently, tire pressure monitoring sensors on the market are primarily categorized as internal and external, with significant differences in installation methods, performance, and applicable scenarios.

(I) Built-in Sensors: The Mainstream Choice, Accurate and Durable

Built-in sensors are the preferred configuration for mainstream vehicles. Their core feature is precision and durability. Installation requires removing the tire from the wheel hub, securing the sensor to the base of the valve stem, then reinstalling the tire and performing dynamic balancing. This installation method places the sensor completely inside the tire, shielded from external interference. Whether it's airflow at high speeds, soaking in rain, or splashing mud and sand on the road, none of these factors affect the sensor's detection accuracy. 

Pressure error is controlled within ±0.1 bar, and temperature detection error does not exceed ±2°C. Furthermore, the battery in these sensors features a low-power design, offering a lifespan of 5-7 years. Some high-end products even offer a 10-year battery life, eliminating the need for frequent replacement.

However, their drawbacks are significant: installation and replacement are complex, requiring specialized maintenance personnel, and replacement costs are high (a single sensor typically costs 150-300 yuan). Replacing all four sensors can cost 600-1200 yuan.

 (II) External Sensors: Preferred for Retrofitting, Convenient and Economical

External sensors are more suitable for retrofitting on older vehicles. Their core advantage is convenience and affordability: Installation requires no tire removal; the sensor simply screws directly onto the tire valve stem and manually tightens. The entire process takes only 5-10 minutes, and the owner can perform the installation themselves.

External sensors are also more affordable, typically costing between 50-100 yuan each, or only 200-400 yuan for four, offering excellent value for money. However, due to its mounting method, its performance suffers from significant shortcomings: exposed sensors are susceptible to external interference. Airflow at high speeds can cause pressure measurement errors (the error can reach up to ±0.3 bar), and dust or rain can affect temperature measurement accuracy.

Furthermore, sensors screwed directly onto the valve stem are susceptible to loss due to collisions (such as curb scrapes) or theft when the vehicle is jolting or parked. Battery life is also short. Because it needs to constantly withstand environmental influences, power consumption is higher, typically requiring replacement every two to three years, and some heavily used vehicles may require replacement every year.

Use and Maintenance: Key to Effective Sensor Operation

Regardless of the type of sensor chosen, proper use and maintenance are crucial to ensuring its effectiveness.

(I) Complete System Matching: Avoid Data Interruptions

First, the sensor must be "matched" with the vehicle's central control system. When a new vehicle leaves the factory, built-in sensors are pre-bound to the central control system, requiring no additional work. However, if an external sensor is added later or a new sensor is replaced, a "learning" (reset) process using dedicated equipment (such as an OBD matching tool) is required to allow the central control system to recognize the new sensor's ID signal. Otherwise, data transmission interruptions and alarm failures may occur.

(II) Pay attention to battery life: Replace promptly to prevent monitoring failure

Second, pay attention to sensor battery life. When the central control system displays "Sensor Battery Low," replace the battery or sensor promptly to avoid tire pressure monitoring failure due to battery depletion. Replacing an internal sensor requires removing the tire again, and it is recommended to check the valve stem seal at the same time.

When replacing the battery in an external sensor, ensure that the sensor is waterproof to prevent rainwater from seeping into the circuitry. 

(III) Daily Cleaning Precautions: Avoid High-Pressure Washing to Damage Components

Finally, special precautions should be taken during daily vehicle cleaning: When cleaning tires, avoid using a high-pressure water gun to directly wash sensors, especially external sensors. High-pressure water can loosen the sensor, allow water to enter, and even damage the internal circuitry.

Although internal sensors are waterproof, prolonged high-pressure washing can also affect the seal between the valve stem and the sensor. It is recommended to gently rinse the tires with low-pressure water.