Have you seen that little yellow horseshoe shape with an exclamation point pops up on your dashboard and suddenly you are worried about a flat? If you pull over and check your air pressure only to find that the tires look perfectly fine, you might start to think that your car is just crying wolf. At our shop, we deal with the Tire Pressure Monitoring System, or TPMS, every single day.
While it can be an annoying light to see, it is actually one of the most important safety features on your vehicle. If that light keeps coming back even after you have added air, there is usually a very logical explanation. Understanding why your car is obsessed with its tire pressure can save you from a lot of frustration and potentially a very expensive repair.
The Mystery of the Changing Weather
The most common reason for a recurring low tire light is actually the weather. You might notice the light comes on during the first cold morning of autumn or when a sudden cold front moves through town. This is not a glitch in the system. It is basic physics.
When the air gets cold, it becomes denser and takes up less space. For every ten degrees the temperature drops, your tires can lose about one pound of pressure. When you start driving, the friction between the tire and the road generates heat. This heat causes the air inside to expand again, which might make the light go out after ten or fifteen minutes. However, the light will just come back the next morning when the tires cool down. The best way to fix this is to check your pressure in the morning when the tires are cold and fill them to the specific level listed on the sticker inside your driver side door frame.
The Problem of the Slow Leak
Sometimes the light keeps coming on because there is a legitimate problem that you just cannot see with your eyes. A tire does not have to be pancake flat to trigger a warning. Most systems will turn on the light if the pressure drops about twenty five percent below the recommended level.
There are several things that can cause a slow, annoying leak that takes days or even weeks to trigger the sensor.
- A Small Nail or Screw: You might have picked up a piece of hardware that is perfectly plugged into the tread. It allows air to seep out very slowly but stays hidden from view.
- A Leaky Valve Stem: The little rubber tube where you add air can dry out and crack over time. If the tiny valve core inside is loose or dirty, it will let air escape.
- Corrosion on the Rim: If you live in an area where salt is used on the roads, the metal rim can develop corrosion right where the tire beads against it. This creates a tiny gap that is very hard to find without professional equipment.
When the Sensor Is the Problem
If your air pressure is perfect but the light stays on anyway, you might be dealing with a faulty sensor. Most TPMS sensors are small electronic devices located inside the tire. They are powered by tiny batteries that are designed to last between five and ten years.
Once that battery dies, the sensor can no longer send a signal to the car computer. This usually causes the light to flash for about a minute when you start the car and then stay solid. Because the sensors are located inside the wheel, they are also prone to damage from deep potholes or even from a technician who is not careful when mounting a new tire. If your car is more than a few years old, there is a good chance that one or more of your sensors have simply reached the end of their lifespan.
Why You Should Not Just Ignore It
It can be tempting to just put a piece of black tape over the light and keep driving, but we really advise against that. Driving on underinflated tires is dangerous for several reasons. It makes your car work harder, which ruins your fuel economy. It also causes the tires to wear out much faster on the edges, meaning you will be buying a new set of rubber much sooner than you should. Most importantly, a low tire creates more heat and can lead to a sudden blowout at high speeds.
The TPMS light is not there to annoy you. It is there to act as an early warning system so you can fix a small problem before it becomes a dangerous one on the side of the highway.
Let Us Clear the Light for You
If you are tired of playing the guessing game with your tire pressure, come see us at Pit Shop Auto Repair. Whether you need a simple patch, a new sensor, or just a professional calibration, we will get it done right the first time. You deserve to drive without a yellow warning light staring you in the face.
Stop by the shop today and let us give you the peace of mind that comes with a perfectly balanced and pressurized set of tires.
