Your TPMS light means one or more tires are underinflated, overinflated, or the sensor itself has failed
The tire pressure monitoring system (TPMS) light on your dashboard — usually a yellow or amber icon shaped like a tire with an exclamation mark — turns on when your vehicle detects a pressure problem. The light can mean your tires have lost air, gained air from heat, or that one of the wireless sensors inside the tire has stopped working. It does not mean you have a flat tire or an when ready emergency, but it does mean you should check your tire pressure within the next few hours of driving.
TPMS became mandatory on all new cars sold in the United States starting in 2008. The system uses small wireless sensors mounted inside each tire (or sometimes on the valve stem) that transmit pressure readings to your vehicle's computer. When pressure in any tire drops about 25 percent below the manufacturer's recommended level, or when a sensor fails to send a signal, the light activates.
Key Takeaways
- Check your tire pressure with a manual gauge within a few hours of the light turning on; the manufacturer's recommended pressure is printed on a sticker inside your driver's door, not on the tire sidewall.
- Cold weather, recent driving, and altitude changes can cause pressure swings that trigger the light without indicating a leak or damage.
- If one tire is significantly lower than the others, you may have a slow leak or puncture that requires a tire shop to inspect and repair.
- A sensor battery typically lasts five to ten years; if pressure is normal but the light stays on, the sensor in that tire has likely failed and needs replacement.
- Driving with the light on is safe for short distances, but ignoring it long-term reduces fuel economy and increases tire wear and blowout risk.
How to check your tire pressure and find the correct PSI
Your vehicle's recommended tire pressure is not the number printed on the tire sidewall. That sidewall number is the maximum pressure the tire can safely hold, not the pressure your car needs. The correct pressure for your vehicle is printed on a white or silver sticker inside your driver's door jamb, on the door itself, or sometimes in the fuel door or owner's manual. It is usually listed as a single number (like 32 PSI) or sometimes as a range for front and rear tires.
To check pressure, buy or borrow a tire pressure gauge — digital gauges are more accurate than stick gauges and cost $10 to $20. Remove the valve cap from one tire, press the gauge firmly onto the valve stem until you hear a small hiss, and read the number. Do this for all four tires (and the spare if your vehicle has a TPMS sensor in it). Compare each reading to the manufacturer's recommended pressure. If any tire is more than 3 to 4 PSI below the target, that is likely why your light is on.
If all four tires are within 2 PSI of the target pressure, the problem is probably a failed sensor rather than low pressure. If one tire is significantly lower than the others, you have a leak.
Why cold weather and driving conditions trigger the light
Tire pressure drops about 1 PSI for every 10 degrees Fahrenheit the temperature falls. If you park your car overnight in cold weather, or if the outside temperature drops suddenly, your tires will lose pressure even though nothing is wrong with them. This is the most common reason the TPMS light turns on in winter, and it usually goes away once the tires warm up from driving or the weather warms up.
Driving itself heats the tires and increases pressure. If your light came on during or when ready after a long highway drive, the pressure may have been borderline low when the car was cold, then the light turned on as the tires warmed and the computer recalculated. Once the tires cool down, the pressure will drop again and the light may turn off on its own.
Altitude changes also affect pressure. Driving up a mountain or flying to a higher elevation can cause pressure to drop; driving down or returning to sea level can cause it to rise. These changes are temporary and usually self-correct within a few hours of driving.
Identifying a slow leak versus a sensor failure
If one tire is consistently 5 PSI or more below the others, you likely have a slow leak. This can be caused by a puncture (from a nail, screw, or sharp object), a damaged valve stem, a cracked wheel, or a bead leak where the tire does not seal properly against the rim. A slow leak will get worse over days or weeks; the tire will lose a few PSI every time you park it.
Take the car to a tire shop and ask them to inspect the tire for leaks. They will usually do this for free or for a small fee ($10 to $20). If they find a puncture in the tread, they can patch it for $15 to $30. If the leak is in the sidewall, near the bead, or in the valve stem, the tire cannot be safely repaired and must be replaced.
If all four tires hold pressure normally but the light stays on, one of your TPMS sensors has failed. Sensors use small batteries that last five to ten years depending on the sensor type and how often the vehicle is driven. A failed sensor must be replaced; you cannot repair it. Replacement costs $50 to $150 per sensor at a tire shop, plus labor.
What to do if the light stays on after you inflate your tires
After you add air to bring all tires to the correct pressure, the TPMS light should turn off within a few minutes to a few hours of driving. The vehicle's computer needs time to receive new pressure readings from all four sensors and confirm that pressure is now normal.
If the light stays on after 24 hours of driving and all tires are at the correct pressure, a sensor has failed. You can continue driving safely, but you will no longer have real-time pressure monitoring for that tire. If that tire develops a slow leak, you will not know until the pressure drops enough to cause visible handling problems or until you manually check it.
Some vehicles allow you to reset the TPMS system manually through the dashboard menu. Check your owner's manual for the reset procedure; it usually involves holding a button or navigating through the instrument cluster settings. Resetting does not fix a failed sensor, but it can clear a false alert if the light turned on due to a software glitch.
When to drive to a tire shop versus continuing to drive normally
If your tire pressure is only slightly low (within 3 to 4 PSI of the target) and the light just came on, you can drive normally to a tire shop or gas station to add air. This is safe and will not damage the tire.
If one tire is very low (more than 10 PSI below target) or if you see visible damage, bulges, or a puncture in the tire, do not drive on it. Call a tow truck or drive slowly to the nearest tire shop. Driving on a severely underinflated tire generates excessive heat and can cause a blowout.
If you cannot see any damage and the pressure is only moderately low, you can drive up to 50 miles at normal highway speeds to reach a shop. Avoid high speeds and heavy acceleration. If the tire feels flat or the car pulls to one side, pull over and call for a tow.
How to prevent the TPMS light from turning on
Check your tire pressure once a month using a manual gauge, even if the light is not on. This catches slow leaks early and prevents the light from turning on unexpectedly. Check pressure when the tires are cold — before you have driven the car, or at least three hours after you have stopped driving — because pressure readings are most accurate when the tires are at ambient temperature.
Before winter, add 2 to 3 PSI to each tire above the manufacturer's recommended pressure to account for the pressure drop that cold weather will cause. This gives you a buffer so the light does not turn on during the first cold snap. Return to the normal recommended pressure in spring.
Have your TPMS sensors inspected every few years, especially if your vehicle is more than five years old. A tire shop can tell you whether the sensors are still functioning and have good battery life remaining. Replacing a sensor before it fails is cheaper than dealing with a failed sensor that leaves you without pressure monitoring.
Frequently Asked Questions
Can I drive with the TPMS light on?
Yes, for short distances. The light does not indicate an when ready emergency. However, driving with underinflated tires reduces fuel economy, increases tire wear, and raises the risk of a blowout, especially at highway speeds or in hot weather. Have the pressure checked and corrected within a few hours.
Does the TPMS light mean I have a flat tire?
No. A flat tire usually causes the light to come on, but the light can also turn on from a slow leak, cold weather, or a failed sensor. Check your tire pressure with a gauge to see which tires are low. A truly flat tire will show zero or near-zero PSI.
Why did the light turn on after I just filled my tires?
The vehicle's computer needs a few minutes to several hours to receive updated pressure readings from all sensors. Drive the car for 10 to 15 minutes at normal speed and the light should turn off. If it stays on after 24 hours, a sensor may have failed or you may have added too much air.
How much does it cost to replace a TPMS sensor?
A single sensor replacement typically costs $50 to $150 at a tire shop, depending on the sensor type and your vehicle. Some vehicles use sensors mounted on the valve stem (cheaper to replace) and others use sensors inside the tire (more expensive). Labor is usually included in the quoted price.
Will the TPMS light turn off on its own if I just wait?
Only if the pressure drop was caused by cold weather or driving conditions. Once the tires warm up or the weather warms, pressure will rise and the light may turn off. If the light stays on for more than a few hours after the tires have warmed, you have a leak or a failed sensor that requires action.