What Your Tire Pressure Warning Light Means and What to Do

The tire pressure warning light means one or more of your tires is underinflated or overinflated

When you see a light on your dashboard shaped like an exclamation mark inside a tire, your vehicle's tire pressure monitoring system (TPMS) has detected that at least one tire is not at the correct pressure. This is not a check engine light — it is a direct message about your tires. The light may be solid or blinking, and either way, you should check your tire pressure within the next few hours.

Tire pressure changes with temperature and driving conditions. Cold weather can drop pressure by 1 pound per square inch (PSI) for every 10-degree drop in temperature. A slow leak, a puncture, or simply a tire that has lost air over time can also trigger the light. In rare cases, the TPMS sensor itself has failed.

Driving on underinflated tires reduces fuel economy, causes uneven wear, and can overheat the tire, raising the risk of a blowout. Overinflated tires wear faster in the center and reduce traction. Either way, the light is telling you to act, not to ignore it.

Key Takeaways

• Check your tire pressure as soon as you can — the correct PSI is printed on a sticker inside your driver's door frame, not on the tire itself.
• Use a tire pressure gauge (available at any gas station or auto parts store for under $15) to measure each tire, including the spare if your vehicle has a TPMS sensor in it.
• If one tire is low, inflate it to the correct pressure; if all four are low, the problem is usually temperature change, not a leak.
• If a tire stays low after you inflate it, you likely have a slow leak and should have that tire inspected by a technician.
• If all tires are at the correct pressure but the light stays on, the TPMS sensor may be faulty and will need replacement.

Find the correct tire pressure for your vehicle

The correct pressure is not printed on the tire itself — that number is the maximum pressure the tire can safely hold. Instead, look for a white or silver sticker on the inside of your driver's side door frame, or check your owner's manual. The sticker lists the recommended PSI for the front tires and rear tires, which may be different.

Write down these numbers before you check your tires. Most vehicles call for between 30 and 35 PSI, but some trucks and SUVs run higher. The sticker also tells you the tire size and load rating, which is useful information to have if you ever need to replace a tire.

Check each tire with a pressure gauge

You will need a tire pressure gauge, which costs $5 to $15 and is available at any gas station, auto parts store, or online. There are three types: stick gauges (cheapest, least accurate), dial gauges (mid-range, more reliable), and digital gauges (most expensive, most precise). Any of them will tell you whether your tire is low.

Remove the valve cap from the first tire — it is a small plastic or metal cap on the tire's outer edge. Press the gauge firmly onto the valve stem until you hear a small hiss of air. The gauge will display the PSI. Write it down. Repeat for all four tires, and check the spare if your vehicle has a TPMS sensor in the spare tire.

Compare each reading to the correct pressure on your door frame sticker. If a tire is 2 to 3 PSI below the target, it is low enough to trigger the warning light. If a tire is 2 to 3 PSI above the target, it is overinflated.

Inflate or deflate tires to the correct pressure

If a tire is low, drive to a gas station or tire shop and use the air pump. Most gas stations have free air; some newer stations charge 50 cents to $1. Attach the pump nozzle to the valve stem, hold it firmly in place, and add air in short bursts. Check the pressure every few seconds with your gauge so you do not overfill.

If a tire is overinflated, you can release air by pressing the small pin inside the valve stem with a small tool (many gauges have one built in). Press gently and check the pressure frequently — it is easier to add air than to remove it.

Once all four tires are at the correct pressure, the warning light should turn off within a few minutes of driving. If it does not, move to the next step.

Identify whether you have a slow leak

If one tire drops below the correct pressure again within a few days or a week, you likely have a slow leak. A slow leak can come from a puncture (a nail or screw), a damaged valve stem, or a crack in the sidewall. Do not ignore it — a slow leak will eventually become a flat tire.

Take the vehicle to a tire shop or mechanic and ask them to inspect the tire for leaks. They will use soapy water to find the leak, and if it is in the tread (the part that touches the road), they can often patch it for $10 to $20. If the leak is in the sidewall or the tire is too worn, the tire will need to be replaced.

If all four tires drop in pressure at the same rate, the problem is usually not a leak but a temperature change. Cold weather is the most common cause. In that case, inflate all four tires to the correct pressure and the light should stay off.

Replace the TPMS sensor if the light stays on

If all four tires are at the correct pressure and the light is still on, the TPMS sensor has likely failed. Each tire has a small wireless sensor that sends pressure data to your vehicle's computer. When a sensor dies, the light stays on even though your tires are fine.

A faulty TPMS sensor must be replaced by a technician. The cost varies widely — from $100 to $300 per sensor depending on the vehicle and the shop. Some sensors are part of the valve stem and some are separate; a technician will know which type your vehicle uses.

In the meantime, continue to check your tire pressure manually once a month. A faulty sensor is an inconvenience, not a safety emergency, as long as you monitor your tires yourself.

Understand the difference between a blinking and solid light

A solid tire pressure warning light means one or more tires is underinflated or overinflated. Check and adjust your tire pressure as described above.

A blinking light that comes on when you start the vehicle and stays on while you drive usually means the TPMS system itself is malfunctioning — either a sensor has failed or there is a problem with the system's computer. This is different from a pressure problem. You should still check your tires manually, but the blinking light is telling you the system needs service.

Frequently Asked Questions

Can I drive with the tire pressure light on?

You can drive short distances, but you should check your tire pressure and correct it as soon as possible. Underinflated tires overheat and wear faster, and overinflated tires reduce traction. If a tire is severely low (more than 10 PSI below the target), do not drive — pull over and call for roadside help.

Why did my tire pressure light come on in winter?

Cold weather drops tire pressure by about 1 PSI for every 10-degree drop in temperature. If the temperature fell 30 degrees overnight, your tires could lose 3 PSI, which is enough to trigger the light. Inflate your tires to the correct pressure and the light should turn off. You may need to do this again if the temperature drops further.

What if I inflate my tires but the light does not turn off right away?

The light may take a few minutes to turn off after you correct the pressure. Drive for 5 to 10 minutes at normal speed and check again. If the light is still on after that, one tire may have dropped again (suggesting a leak), or the TPMS sensor may be faulty.

Is it safe to ignore the tire pressure warning light?

No. Underinflated tires are a safety hazard — they overheat, wear unevenly, and can fail suddenly. Overinflated tires reduce your vehicle's grip on the road. Check your tire pressure within a few hours of seeing the light.

How often should I check my tire pressure?

Check your tire pressure at least once a month, and again whenever the temperature changes significantly. Many people check in the fall and spring when they change their clocks. Checking takes five minutes and can prevent a flat tire or a safety problem.