How does a tire pressure monitoring system work

How Does a Tire Pressure Monitoring System Work?

A tire pressure monitoring system (TPMS) apparently does a simple job—monitoring the air pressure in your car’s tires. It’s a safety accessory that warns drivers about underinflated tires. How does a tire pressure monitoring system work? Have you ever wondered about it?

Well, wonder no more. In this post, we’ll look at how these handy systems keep track of your tire pressure and alert you when it’s time to add air.

The Importance of Correct Tire Pressure

Maintaining correct tire pressure in any vehicle is essential for two reasons. First, it helps improve your gas mileage. Second, it prolongs the life of your tires.

According to the U.S. Department of Energy, a drop of 1 psi in tire pressure can decrease gas mileage by 0.4%. Low tire pressure also causes your tires to flex more, which generates heat and can damage the tire structure.

Overinflated tires don’t grip the road like properly inflated tires, leading to a blowout or other accidents. Also, incorrect tire pressure affects riding stability, which may lead to fatal accidents.

TPMS symbol
The TPMS symbol on the dashboard. Photo: Edmunds

How Does a Tire Pressure Monitoring System Work?

There are two types of TPMS: Indirect system vs direct system

Both systems warn about underinflated tires by triggering a light on the dashboard. The yellow symbol looks like a horseshoe with an exclamation sign in the center.

We will discuss the mechanism of both systems for your better understanding.

Mechanism of an Indirect Tire Pressure Monitoring System

An indirect TPMS uses wheel speed sensors to infer the pressure of a vehicle’s tires. It’s a software-based system that collects data from the ABS and traction-control system.

When a vehicle’s tires are inflated to the proper pressure, they rotate at a consistent speed. The rotation speed of underinflated tires will be different from the regular ones.

An underinflated tire is smaller than a regular one, so it will spin faster, which will trigger the sensor. An indirect TPMS can determine underinflation by measuring the rotational speed of the wheels.

Indirect TPMS systems have several advantages over direct TPMS systems. They are less expensive to manufacture and easier to install. Since there is no physical sensor, it will work fine even if the car is hit by potholes or something else.

However, indirect TPMS systems are less accurate than direct TPMS systems and may not be able to detect minimal changes in tire pressure. Additionally, they cannot compensate for differences in air temperature, which can affect tire pressure. For these reasons, many newer vehicles are equipped with direct TPMS systems.

Mechanism of a Direct Tire Pressure Monitoring System

How does a tire pressure monitoring system work when it’s a direct system? A direct TPMS uses sensors to monitor vehicle tires’ air pressure. You will find the sensors on the wheels or inside the tires. They send data to a receiver installed on the vehicle, which interprets the data and displays it on a dash-mounted display.

The purpose of a TPMS is to keep track of the air pressure in each tire and warn the driver if any tires are low on air. This information can help prevent flats and blowouts, and it can also improve fuel economy.

Most modern cars have this system because it provides accurate data.

How Does a Tire Pressure Monitoring System Work? 1
A direct TPMS. Photo: Wikiwand

Can a Tire Pressure Monitoring System Break Down?

There are a few ways a TPMS can fail. The most common way is for the sensor to dislodge the valve stem. You can experience it when the car hits a pothole or go over a curb too quickly. It can also happen when you don’t put the sensor back in the correct position after changing the tires.

Another way TPMS can fail is if the battery in the sensor dies. Most sensors have a battery life of about five to ten years, but the duration is five to six years for older sensors. So, if your car is more than five years old, there’s a chance the TPMS is no longer working.

You’ll know the sensor’s battery is dead if the light on your dashboard indicates tire pressure comes on even though all your tires are properly inflated.

If your TPMS light comes on and you’re not sure why, it’s always best to take professional help. A mechanic can surely tell you whether or not the system is working correctly.


How does a tire pressure monitoring system work? You must have had a clear idea already. The electronic system functions by using a simple formula: warning the driver when the pressure in one or more tires falls below a certain level. All cars manufactured after 2007 have this small but effective system installed.

Most modern vehicles have the direct system because of its accuracy. However, the indirect system has also improved a lot because of new technology.

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