How the TPMS Works

How the TPMS Sensors WorkThe Tire Pressure Monitoring System (TPMS) is an essential tool for drivers to let them know if their vehicle’s tire pressure is normal or if something may be amiss. The TPMS is part of your onboard diagnostic system that communicates to you through your dashboard. This system monitors the pressure in each of your tires to alert you if one or more of the tire’s air pressure has fallen below the ideal PSI (pounds per square inch) recommended for your vehicle.

You may recognize the TPMS symbol as an exclamation point inside of a horseshoe with ridges on the bottom similar to tire treads. This system is considered a safety feature and is now required to be equipped in all newer vehicles. Learn how TPMS sensors work and how they alert you to potential troubles related to your tires.

Why Do Cars Have TPMS?

TPMS was first introduced in the early 1980s in mostly European luxury vehicles. In 1997 the first American car, the Chevrolet Corvette, introduced the monitoring system. TPMS was not required until about ten years later, however. In 2000, prompted by the attention from serious injuries and fatalities related to tire pressure incidents, the U.S. Government passed the TREAD Act that mandated several new safety standards as well as required that by 2007, automotive manufacturers equip all new vehicles with TPMS.

Does My Car Have TPMS?

Most cars and light trucks produced in 2008 and later are equipped with some form of Tire Pressure Monitoring Systems. Refer to your owner’s manual for confirmation. Vehicles that do have TPMS will have a warning light displayed on the vehicle’s dashboard if one or more of the tires falls below the recommended pressure as set by the vehicle and tire manufacturer.  

How Does TPMS Work?

There are two types of monitoring systems that are used for TPMS: Direct or Indirect TPMS.

Direct TPMS utilizes a sensor that is affixed to the wheel to measure the air pressure in each tire. Once the air pressure drops past 25% of the recommended pressure, the sensor communicates the level to the car’s internal computer and causes the light to illuminate.

Indirect TPMS is part of the car’s Antilock Brake System (ABS) wheel speed sensors. When tire pressure is low, the wheel rolls at a different speed compared to the other tires. The car’s internal computer recognizes the difference and illuminates the light on the dashboard.

Why TPMS Is Important

Caring for your tires is vital to your safety on the road. Ensuring your tires are properly inflated is one of many ways to care for your tires. Tires that are over or underinflated cause premature wear that may require early replacement.

Overinflated tires reduce traction, increase wear, and struggle to make contact with the road due to excess wear in the center tread. Underinflated tires are a risk to your safety on the road because driving on underinflated tires creates immense heat that results in tire blowouts that could cause severe accidents.

Properly inflated tires on the other hand, are able to maintain better contact with the road, which increases your vehicle’s handling. Properly inflated tires also:

  • Extend the life of the tire
  • Direct water away from the tires when traveling over wet surfaces
  • Increase fuel efficiency by reducing rolling resistance
  • Provide a cushion for comfort while traveling over rough surfaces
  • Provide better support for the weight of the vehicle
  • Make controlling the vehicle during braking, acceleration, and cornering easier on the driver
  • Disperse heat created from movement

Do I Still Need to Check My Tire Pressure with TPMS?

Absolutely. TPMS is a fantastic tool but it should not be used as a substitute in checking and maintaining your tire pressure. Relying solely on your TPMS system is a risk because the sensors could be malfunctioning and inaccurately transmitting data to your vehicle’s computer, the system may be set to alert you well below the necessary pressure needed to support the weight of the vehicle, and it may not be able to accurately determine if a tire is dangerously low or if other tires are also losing pressure. The sensor is programmed to turn on the warning light when the pressure is about 3lbs above or below the manufacturer’s recommended pressure.

How to check your tire’s air pressure:

  1. Locate the required pressure level often located on the yellow sticker placed on the frame of the driver’s side door or the owner’s manual. Keep in mind, based on your vehicle type, your vehicle’s front tire pressure may vary from rear tires.
  2. Remove the valve cap and press the tire gauge onto the valve stem. The gauge will instantly provide a number that translates to the PSI of the tire.
  3. Based on the PSI reading, add or release air as necessary to achieve the ideal air pressure required for your tires.

Note: be sure to check tire pressure when your tires are “cold”, meaning before you have driven the vehicle.

Can TPMS Malfunction?

Just like many components on your vehicle, over time the sensor can wear out. Sensors typically last between 5 and 10 years. TPMS malfunctions can occur due to worn sensor seals, damage to the sensor, dead sensor battery, or transmission to the on-board computer fails. When your Tire Pressure Monitoring System is in failure, the light on the dashboard may come on, though tire pressure is accurate, or the system’s light may flash on and off. In either case, it’s best to take your vehicle to an automotive professional to resolve the issue right away.