You may have never asked yourself what is a tire pressure monitor sensor. These sensors do exactly what you’d expect; they monitor the pressure within your tires. However, because these sensors are battery powered, over time they will fail and you will need to replace or know how to repair tire pressure monitor sensors. Don’t worry too much about this, when the time comes you will be warned via the little TPMS on your dash and it is a fairly cheap fix. A little fact about tire pressure is that if you are driving on tires that are 10% under inflated, you will see a 1% decrease on your gas mileage.
As of 2007, the NHTSA requires the installation of these sensors on all vehicles. There are two types of these sensors, direct and indirect. Direct tire pressure monitoring sensors are located either inside or outside the tire and they physically measure the pressure. After doing so, they report this information to the instrument cluster of the vehicle. Newer vehicles can display real-time pressures of each tire while driving or parked. Indirect sensors on the other hand don’t actually detect the tire pressure, but they “infer” the pressure through various factors. The main factor is the rotational speed of each individual wheel. If a tire has less pressure, the diameter will be slightly smaller and in turn will spin a bit faster.
Regardless of which type of sensor your vehicle uses, if that warning light comes on DON'T just pretend its not there and put off the job. It is important, and cheap, to fix this issue. Not only can they save you a few extra dollars at the pump, but if they are working properly you will have lower emissions, increased handling of your vehicle, and you won't have to worry about failing that state inspection coming up. Also an under inflated tire is the leading cause of tire failure, so having your sensors in working order will increase your tire life.