Your tire pressure monitor light means one or more tires are underinflated, overinflated, or the sensor itself has failed
The tire pressure monitoring system (TPMS) in your vehicle watches the air pressure in each tire and alerts you when something is wrong. When that light appears on your dashboard — usually a yellow exclamation mark inside a tire shape — it means at least one tire is about 25% below the manufacturer's recommended pressure, or the system has detected a sensor malfunction. This is not an emergency, but it does need attention within a few days.
The light can mean three different things: a tire has lost air (the most common cause), you've overinflated a tire, or a sensor battery has died. You'll need to check your tires to know which one. The manufacturer's recommended pressure is printed on a sticker inside your driver's door jamb, not on the tire sidewall itself — the sidewall shows the maximum pressure the tire can hold, which is different.
Key Takeaways
- Check all four tire pressures with a manual gauge within a day of the light appearing, because a slow leak can worsen quickly.
- The correct pressure is on the door jamb sticker, not the tire sidewall, and varies by vehicle weight and suspension setup.
- A tire that's 3 to 5 pounds per square inch (PSI) below spec usually means a slow leak, which requires a patch or replacement.
- TPMS sensors last 5 to 10 years and cost $50 to $200 per sensor to replace when the battery dies.
- Seasonal temperature swings can drop tire pressure by 1 PSI for every 10 degrees Fahrenheit, which sometimes triggers the light without any leak.
How to check your tire pressure yourself
You need a tire pressure gauge, which costs $5 to $15 at any auto parts store or gas station. A digital gauge is easier to read than an analog dial, but both work. Remove the valve cap from one tire, press the gauge firmly onto the valve stem until you hear air stop hissing, and read the number. Write down the pressure for all four tires, then compare each to the number on your door jamb sticker.
Check the tires when they're cold — meaning the car has been parked for at least three hours or driven less than a mile. Tire pressure rises as the tire heats up from driving, so a warm tire will read 3 to 5 PSI higher than the true pressure. If you check after driving, you'll get a false high reading and may miss a real problem.
If all four tires are within 2 PSI of the recommended pressure, the light may be a sensor fault. If one or more tires are 3 PSI or more below spec, you have a leak. If a tire is 5 PSI or more above spec, you've overinflated it — this can happen if you filled it at a gas station pump that was set too high.
What to do if a tire is underinflated
A tire that's 3 to 5 PSI low usually has a slow leak. You can add air at a gas station (most have free air pumps), but the pressure will drop again within days or weeks. A slow leak means the tire has a puncture, a cracked sidewall, or a faulty valve stem. Driving on an underinflated tire wears it faster, reduces fuel economy, and can cause overheating in hot weather.
Take the car to a tire shop or mechanic and ask them to find the leak. They'll pressurize the tire and listen or look for escaping air. If the leak is in the tread (the part that touches the road), it can usually be patched for $10 to $25. If the leak is in the sidewall or the valve stem, the tire must be replaced. A patch is temporary and is not safe for highway driving on some vehicles, so ask the shop whether patching or replacing is recommended for your situation.
Do not ignore a slow leak. A tire that loses pressure gradually can fail suddenly if you hit a pothole or drive at highway speed for a long distance. The tire can overheat, separate from the rim, or blow out.
Temperature changes and seasonal pressure drops
Tire pressure drops about 1 PSI for every 10 degrees Fahrenheit that the outside temperature falls. In autumn and winter, when temperatures drop 30 to 50 degrees from summer, your tires can lose 3 to 5 PSI without any leak occurring. This is why the TPMS light often comes on in late fall or early winter, even on cars that had no problems in summer.
If you check your tires and find they're all 2 to 4 PSI below spec, and the temperature has dropped recently, add air to bring them back to the recommended pressure. The light should turn off within a few minutes of driving. If the pressure drops again within a week, you have a leak rather than a temperature issue.
When the TPMS sensor itself has failed
TPMS sensors are small battery-powered devices mounted inside each tire. The batteries last 5 to 10 years, depending on the sensor brand and how often the system transmits data. When a battery dies, the sensor stops sending pressure readings to your vehicle's computer, and the light comes on.
If you've checked all four tires and they're all within 2 PSI of the recommended pressure, the problem is almost certainly a dead sensor. A mechanic can use a TPMS diagnostic tool to identify which sensor has failed. Replacing one sensor costs $50 to $200 depending on your vehicle — some cars use straightforward sensors, while others use more complex ones that integrate with the wheel.
You can drive safely with a dead sensor for a while, but you lose the warning system if a tire does develop a leak. Most people replace the sensor within a month or two. If multiple sensors fail at once, it usually means they're all reaching the end of their lifespan, and replacing all four at the same time is more cost-effective than replacing them one at a time over the next year.
Overinflated tires and what to do
If your gauge shows a tire is 5 PSI or more above the recommended pressure, let air out by pressing the small pin inside the valve stem with a thin tool. Press gently and briefly — air will hiss out quickly. Check the pressure again after a few seconds. It's easier to let air out than to add it, so go slowly.
Overinflated tires wear faster in the center of the tread, reduce traction in wet conditions, and make the ride harsher. They're also more prone to punctures from road debris. Once you've brought the pressure down to spec, the light should turn off within a few minutes of driving.
When to replace the tire instead of patching
A tire can be patched if the puncture is in the tread area (the part that touches the road) and is smaller than 1/4 inch across. Punctures in the sidewall, multiple punctures, or punctures larger than 1/4 inch mean the tire must be replaced. A tire shop can tell you which option applies to your tire.
Tire replacement costs $100 to $300 per tire depending on the size and quality. Budget tires cost less but wear faster and may not handle as well in wet conditions. Mid-range tires are a good balance for most drivers. If you replace one tire, many mechanics recommend replacing two at a time (on the same axle) to keep the vehicle balanced, though this depends on how worn the other tires are.
Frequently Asked Questions
How long can I drive with the TPMS light on?
If the light is on because of a slow leak, you can drive for a few days while you arrange a repair, but not longer. Check the tire pressure every day — if it's dropping more than 1 PSI per day, the leak is getting worse and you should not drive at highway speeds. If the light is on because of a dead sensor, you can drive indefinitely, but you've lost your warning system if a tire develops a leak.
Will the light turn off by itself if I add air?
Usually yes, but not when ready. After you add air and bring the tire to the correct pressure, drive the car for a few minutes at normal speed. The TPMS computer needs to receive new readings from the sensors and confirm the pressure is correct. The light should turn off within 5 to 20 minutes of driving. If it stays on after an hour, you may have a sensor problem rather than a pressure problem.
Can I ignore the TPMS light if I'm only driving short distances?
No. Even on short trips, an underinflated tire wears faster and can overheat. A tire that's severely underinflated can fail suddenly, and a blowout at any speed is dangerous. Check your pressure within a day and repair the leak or sensor as soon as you can.
Do I need to replace all four TPMS sensors at once?
Only if all four sensors are failing at the same time, which is rare. If only one sensor has a dead battery, replace just that one. If two or three sensors fail within a few months of each other, they're probably all reaching the end of their lifespan, and replacing all four together may be more economical than replacing them one at a time.
What's the difference between the door jamb pressure and the tire sidewall pressure?
The door jamb sticker shows the pressure your tires should have when cold, based on your vehicle's weight and suspension. The sidewall shows the maximum pressure that tire can safely hold — it's usually 10 to 20 PSI higher. Always use the door jamb number, not the sidewall number.