That annoying but vital light on the dashboard

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Last week I picked up a nail in my tire. The Tire Pressure Monitor System saved me. Let’s explore what your TPMS light actually means and how it does it.
First off, this is great technology. I picked up a screw, and as soon as the tire lost air pressure, the car told me there was a problem. I could not look at that tire and visually see it was 9 pounds low. In an older car, I’d have just driven around until the screw loosened up in the tire and the leak got bigger and faster, maybe ruining the tire by driving on it while flat.
TPMS watches tire pressure in one of two ways. The most common is a pressure sensor and a tiny little transmitter in each wheel which reports what pressure it is at to the car’s computer. There is a second system that integrates the Antilock Brake System. This one works on rotation. Your ABS system monitors and compares the rotation of each wheel on the car. If one wheel is turning more slowly than another, there is a little program which figures out the tire pressure and reports to the car’s computer. Very clever “Black Art”.
Most newer systems can display each tire’s pressure on the dash, so if the light is on, check your pressures, then check the tire that is low. Add air to bring it up to pressure. If the light comes back on, get to the shop and have it checked. You may save yourself the cost of a new tire, not to mention getting stranded on the road.