Q: How Does My Car Monitor Tire Pressure?

asked by on November 16, 2015

How does my car monitor tire pressure?

All of the cars built today come equipped with a tire pressure monitoring system (TPMS). This did not become a requirement until about 2006. At that time, it was determined that a vehicle can be much safer if the driver receives notification of a low tire. If your vehicle is equipped with a TPMS, you will either get a notification of the exact tire pressure, or simply a Low Pressure Light on the dash when a tire is below a specified pressure. Although most vehicles are slightly different from one another, their TPMS systems will all work on the same principle.

The TPMS uses a special pressure sensor that is located inside of the tire. The majority if the time, this sensor is mounted on the inside of the wheel at the valve stem. On some vehicles, it is strapped to the middle of the wheel itself. No matter which kind, they work in the same way. These sensors will detect the pressure on the inside of the tire and send a signal to the computer, which allows it to calculate pressure. Some vehicles will then show the actual pressure reading on the dash, while others will only turn on a warning light when the tire pressure reaches a minimum threshold; typically around 25 psi. In such a case, the tire pressure should be adjusted in order for the light to turn off. It is important to know that on some vehicles, the light may not turn off right away; the vehicle may need to be driven at a particular speed for a certain amount of miles until the computer registers the sensor. Some spare tires will also have a pressure sensor in them, so it is important to check the air in the spare regularly.

Tire pressure sensors can fail for many reasons. A sensor may fail because the battery in it no longer functions, and needs to be replaced, but the most common cause of failure is breakage. A sensor can break from hitting something like a pothole in the road too hard, or it can be damaged when a tire is changed or repaired at a tire shop. If a sensor breaks, it will also need to be replaced. One thing that you need to keep in mind is that when a new sensor is installed, it will not automatically work with the vehicle; the vehicle’s computer needs to pick up the signal from the sensor, so the sensor needs to be programmed into the computer. This is best done with a computer scan tool by a certified mechanic.

In sum, if you get a Low Pressure Light, you need to check the air in the tires. If the tire pressure is fine, then you may have a bad sensor. It is important that you replace any bad tire pressure sensors to keep the TPMS working properly, because maintaining correct tire pressure will not only keep you safe on the road, it can also help maintain your fuel mileage.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

After new front bearings/hubs, Lexus still making noise and shaking

Hello, thank you for writing in. Feeling steering and suspension issues in the steering wheel is very common. While everything you have done is within reason, there are several components that need to be inspected or tested. You will want...

I have really bad shaking in my tires when I drive between 20 and 70 mph

Several things could be causing the shake you're experiencing: tires out of balance, defective/worn tires, worn struts, worn control arm bushings, worn tie rods, wheel bearings starting to fail, the list goes on. Start by having a local service center...

Nissan Altima rumble

The rumbling is caused by an imbalance problem with one of your axles or one or more of the tires. Even though you had the tires balanced, that does not mean your tires do not have a balance issue at...

Related articles

How Does My Car Monitor Tire Pressure?
You’re You’re driving home from work and your steering wheel begins to pull. It gradually gets worse, then you hear a thump-thump-thump noise. You stop on the side of the highway to investigate, only to find you’ve got a flat...
How Does My Car Monitor Tire Pressure?
You’re You’re driving home from work and your steering wheel begins to pull. It gradually gets worse, then you hear a thump-thump-thump noise. You stop on the side of the highway to investigate, only to find you’ve got a flat...
How to Tell if Your Spare Tire Is Still in Good Condition
The The most neglected safety device your car is equipped with is your spare tire. It hides in your trunk or under the back of your vehicle and you don't give it a second thought until you really need it....