That little tire light on your dashboard just came on. The one that looks like a flat tire with an exclamation mark inside it. You have no idea what it means, and now you are wondering if your tire is about to blow out on the highway.
Take a breath. That light is your TPMS, which stands for Tire Pressure Monitoring System. It is telling you that at least one of your tires is low on air. It does not always mean something is wrong with the tire itself, but you should not ignore it either.
Here is what it actually means, what causes it, and what you should do about it.
What Is TPMS and Why Does Every Car Have It?
TPMS has been required on every new vehicle sold in the United States since 2007 and in Canada since 2008. Each tire has a small sensor inside it, usually mounted to the valve stem, that monitors air pressure in real time. When the pressure drops about 25 percent below the manufacturer’s recommended level, the light comes on.
There are two types. Direct TPMS uses actual pressure sensors inside each tire. Indirect TPMS uses your vehicle’s ABS wheel speed sensors to detect differences in how fast each tire is rotating, which changes when a tire loses air. Most vehicles on the road today use the direct system.
5 Common Reasons Your TPMS Light Comes On
Not every TPMS warning means you have a flat or a puncture. Here are the most common causes.
Temperature drop. This is the number one reason people see the light in the morning. Tires lose about 1 PSI for every 10 degree drop in temperature. A cold snap overnight can easily trigger the warning, especially if your tires were already on the low side. This happens a lot in spring and fall when daytime temperatures are warm but nights get cold.
Slow leak. A nail, screw, or piece of metal in the tread can cause a slow leak that drops pressure gradually over days or weeks. You might not notice anything while driving, but the sensor picks it up before you would.
Tire not sealed properly. If you recently had tires mounted or a repair done, the bead might not be sealed perfectly against the rim. Corrosion on the rim can also cause small air leaks.
Bad TPMS sensor. The sensors run on small batteries that last about 5 to 10 years. When the battery dies, the sensor stops reporting and the light comes on. If the light is flashing for about 60 to 90 seconds when you start the car and then stays solid, that usually means a sensor issue rather than a pressure issue.
Recent tire service. After a tire rotation, new tire install, or even airing up at the gas station, the system sometimes needs to recalibrate. Some vehicles reset automatically after a few miles of driving. Others need a manual reset.
What to Do When Your TPMS Light Comes On
First, do not panic but do not ignore it. Here is a simple step by step.
Check your tire pressure. Use a gauge or stop at a gas station with an air pump. Check all four tires plus the spare if your vehicle has one. The recommended pressure is on the sticker inside the driver’s door jamb, not on the tire sidewall. The number on the sidewall is the maximum pressure the tire can handle, not what you should fill it to.
Fill any low tires. Add air to any tire that is below the recommended PSI. If the light was caused by temperature, this usually fixes it immediately.
Look for visible damage. Walk around the vehicle and look for anything stuck in the tread, any bulges in the sidewall, or any tire that looks noticeably lower than the others.
Drive for a few minutes. Many vehicles need to be driven at 20 mph or more for a few minutes before the system rechecks and turns the light off. If it goes off, you are good.
If it comes back on. A light that keeps returning after you fill the tire means you likely have a slow leak or a sensor problem. This is when you want to have a tire professional take a look.
When You Need a Professional
Some TPMS situations are easy to handle yourself. Others are not. You should call a tire tech if the light comes back within a day or two after filling. If the light flashes before staying solid, that points to a sensor failure that needs diagnosis. If you can hear air hissing or the tire is visibly flat, do not drive on it.
A mobile tire tech can come to wherever you are, check all four sensors, find the leak if there is one, and either repair or replace the tire on the spot. No tow truck. No sitting in a waiting room. They pull up, handle it, and you are back on the road.
If you need a sensor replaced, most mobile techs carry the common universal sensors and can program them to your vehicle right in your driveway. Sensor replacement usually takes about 15 to 20 minutes per tire.
Frequently Asked Questions About TPMS
Can I drive with the TPMS light on?
You can drive short distances carefully, but you should check your tire pressure as soon as possible. Low pressure increases the risk of a blowout and reduces fuel economy. If the tire looks flat or you hear hissing, do not drive on it.
How much does it cost to replace a TPMS sensor?
TPMS sensor replacement typically costs between $50 and $150 per sensor including programming. A mobile tire tech can usually handle this at your location without a shop visit. Many techs replace sensors during a tire install at a discounted rate.
Why does my TPMS light come on when it gets cold?
Tire pressure drops about 1 PSI for every 10 degree Fahrenheit decrease in temperature. If your tires are already near the low threshold, an overnight cold snap can push them below the trigger point. Filling to the recommended PSI when temperatures are at their coldest gives you a buffer.
Can a mobile tire tech fix TPMS problems?
Yes. Mobile tire technicians carry diagnostic tools, universal TPMS sensors, and programming equipment. They can diagnose whether the issue is low pressure, a leak, or a bad sensor, and fix it on the spot. Find a verified mobile tire tech near you at MobileTireServices.com.
That dashboard light is doing its job. It is trying to keep you safe. Now you know what it means, what to check, and when to call in a pro. If you need a mobile tire tech who can come to you, check the directory at MobileTireServices.com and find someone in your area.
