How Do Tire Pressure Sensors Work? (Full Guide + FAQs)

Tire pressure is one of the most critical elements in keeping your tires in good shape, therefore, you need to keep track of it.

Fortunately, car models come fitted with tire pressure sensors to alert drivers when there’s a problem. So, how exactly do tire pressure sensors work? To learn all you need to know on this topic, keep reading!

How Do Tire Pressure Sensors Work?

Tire pressure sensors, commonly known as TPMS, are programmable electronic devices located on the inner part of the rim. These sensors are added to the tire to measure the pressure inside the tire. When the pressure drops 25% below the recommended level, the sensors send a warning to the driver by displaying a light on the dashboard.

For more information about tire pressure sensors, how they work, where they’re located, and how long they last, keep reading for more facts!

What Are Tire Pressure Sensors?

Tire pressure sensors, better known as the Tire Pressure Monitoring System (TPMS), use a sensor mounted on the wheel to measure the tire pressure in all four wheels. These systems were introduced due to the high cases of accidents caused by underinflated tires.

According to NHTSA data, TPMS reduces the likelihood that a car will have severely underinflated tires by 56%. When this happens, there’s a reduced risk of getting into accidents.

TPMS was first installed in vehicles manufactured from 2007, due to the U.S. Congress passing the Transportation Recall Enhancement Accountability and Documentation (TREAD) Act.

Since 2014, TPMS has become mandatory for new car models in the European Union. Based on this legislation, all cars were required to have some form of TPMS to monitor the tire pressure.

How Do These Tire Pressure Sensors Work?

How Do These Tire Pressure Sensors Work?

Automakers install TPMS to prompt the driver when the tires are underinflated. When the tire pressure drops 25% below the manufacturer’s recommended levels, the sensors within the tire send information to modules in your car.

These sensors transmit this data via a low-frequency radio to the car’s computer system, which displays an amber light warning on the dashboard.

As a safety and driving assistant feature, these tire sensors ensure that the tires don’t get to a dangerous level of deflation, which can further damage the rim.

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There are two types of tire pressure monitoring systems in the market today, direct and indirect, which determine how the sensors work, which are examined in further detail below:

Direct TPMS

Direct tire pressure monitoring systems use the sensors in each tire to measure the tire pressure. It’s the most common system and is usually mounted on the rims inside the tire.

Apart from the pressure, these sensors also measure the tire temperature and send this information to the car’s information system to warn if low or too much pressure.

Once this data is transmitted to a centralized control module, it’s analyzed and interpreted, and the warning light illuminates on the dashboard.

Direct TPMS systems have five parts, four sensors on each tire and the car’s computer system indicator. Every sensor has a unique serial number, making it easier to identify the specific communication.

Each of these sensors has a battery that’s not serviceable; therefore, it has to be changed when either is damaged.

Changing these sensors is costly because every time a sensor is changed, it has to be reprogrammed into the control module. Additionally, manufacturers use proprietary technology, meaning car owners need to hire experienced technicians for repairs.

Indirect TPMS

On the other hand, indirect tire pressure monitoring systems rely on wheel speed sensors that the anti-lock braking systems (ABS) use.

Unlike the direct sensors, these ones monitor the wheel rotation and use the wheel speed sensor data.

For instance, if a tire is underinflated, it will rotate at a different speed than the others, which is transmitted to the vehicles’ monitors. This data is then analyzed and interpreted by the computer system, which triggers the dashboard warning light.

Indirect TPMS doesn’t measure the actual tire pressure, but measures how fast or slow your tires are turning. In this case, underinflated tires will spin faster than expected.

Overall, these systems are less expensive than direct ones and require less programming and maintenance.

Where Are The Tire Pressure Sensors Located?

Like most drivers, you may be wondering where the tire pressure sensors are located.

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These sensors are located on a pressurized pocket inside the wheel, which enables them to measure the tire pressure accurately.

However, there are some aftermarket systems that are mounted outside the tire. If you’re not sure about the location of your sensors, you can ask a professional mechanic to show you.

What Should You Do When Yout TPMS Light Comes On?

What Should You Do When Your Warning Light Comes On?

As established earlier, the warning light comes on your dashboard if your tire pressure doesn’t align with the recommended PSI.

Therefore, when the light comes on, you need to take the necessary steps to fix the air pressure issues. You can use your tire pressure gauge to determine which tire has lower levels.

Once you get the reading, you need to fill up the remaining balance according to the manufacturer’s recommendation as soon as you can.

If your light comes on again after filling up your tires, you might have a leak that gradually releases the pressure. When this happens, you need to visually inspect your tires for cracks or cuts (you can also check if all the nozzles are well tightened).

However, if the problem persists, you might need to have the tires replaced.

How Do Tire Pressure Sensors Get Power?

TPMS is powered by batteries that are designed to last several years. These batteries can’t be charged; therefore, the entire system has to be replaced when they die.

How Long Do Tire Pressure Monitoring Systems Last?

TPMS sensors have lithium-ion batteries that can last from five to ten years, which get replaced depending on the type.

This question is common among car owners who need to know when to replace their TPMS sensors.

When it’s time to replace the TPMS, it’s mainly due to corrosion, damage, or run-down batteries.

Over time, these sensors face damage due to their location, and can be harmed when you have a flat tire, when you hit a pothole or have an accident.

On the other hand, corrosion happens if you drive during winter on roads that have road salt, as road salt can reach the sensors and lead to excessive corrosion.

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Like other electronic devices, these sensors use batteries that run out of power over time. When this happens, you have to replace the sensors and reconfigure them to the control module.

If your batteries are almost to the end of their life cycle, you can replace the sensors when replacing tires to save labor costs.

Unfortunately, the tire TPMS sensors can’t be repaired, meaning you’ll need to replace the entire system when one gets damaged. Therefore, you need to check and maintain your tires regularly.

How Much Does It Cost To Replace A Tire Pressure Sensor?

How Much Does It Cost To Replace A Tire Pressure Sensor?

If your pressure sensors need to be replaced, it will cost you about $50 to $250. According to reliable sources, some drivers have been charged $75 to $150.

Note that sensor prices vary depending on the type you purchase and the labor costs for the person who installs it for you.

Can You Drive With A Broken TPMS Sensor?

Although the vehicle can be driven when the TPMS sensor is broken, it’s recommended to have it fixed as soon as possible.

When the TPMS is not functioning properly, you won’t get the warning light when the tires lose pressure, which is quite dangerous because it could damage your tire and rims and cause you to lose control of your car.

Overall, driving with a broken TPMS sensor increases your chances of getting into an accident.

To learn more, you can also read our posts on why is the tire pressure light still on after filling tires, if you can turn off the tire pressure monitoring system, and if you can put air in a flat tire.

Conclusion

Tire pressure sensors or TPMS is one of the most critical components in a vehicle. They are located on the inner part of the tire to measure the pressure inside the tires.

When the pressure drops 25% below the recommended levels, the sensors transmit information to the vehicle’s control module and display a warning light on the dashboard.

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