Tire Pressure Light On: What It Means and How to Fix It

The tire pressure light looks like a horseshoe with an exclamation point inside. It comes from the TPMS (tire pressure monitoring system), and when it is on steady it means at least one tire is noticeably under-inflated.

The fix is often just adding air, especially when the weather turns cold. Tire pressure drops about 1 PSI for every 10°F drop in temperature, so the first cold morning of fall turns on a lot of these lights. A flashing light is different and means the monitoring system itself has a problem.

When to stop driving

Pull over safely if the light comes on along with a thumping sound, the car pulling to one side, or the steering feeling heavy or wobbly. Those can mean a tire is going flat. Driving on a very low tire can destroy it and cause a blowout.

Most common causes

A tire is low on air

Tires slowly lose air over time. One or more is below the recommended pressure. This is the most common cause.

Cold weather

Cold air takes up less space, so pressure drops on cold mornings. The light may come on overnight and go off after you drive and the tires warm up.

A slow leak or puncture

A nail, screw, leaking valve stem, or a bad seal at the rim lets air out. If one tire keeps going low, look for a leak.

Dead or damaged TPMS sensor

Each wheel has a sensor with a battery that lasts years, not forever. A dead or damaged sensor makes the light flash for about a minute at startup and then stay on.

Sensors not relearned after tire work

After rotating tires, installing new ones, or putting on the spare, some cars need the system reset or relearned before the light goes off.

What you can safely check yourself

Check all four tires (and the spare, on some cars) with a tire pressure gauge before driving, when they are cold.
Fill each tire to the pressure on the sticker inside the driver’s door jamb, not the maximum number printed on the tire.
Look for nails, screws, or cuts in the tread, and listen for hissing. Spraying soapy water on the tire shows a leak as bubbles.
Notice whether the light is steady (low tire) or flashes for about a minute and then stays on (sensor or system problem).
After filling the tires, drive for 10 to 20 minutes. Many cars turn the light off on their own; others have a reset button or menu setting in the owner’s manual.

Step-by-step guides

Check and fill tire pressure

Beginner · 5–15 minutes

When to call a mechanic

Go to a tire shop if one tire keeps losing air, if the light flashes at startup (sensor problem), or if the light stays on after all tires are filled correctly and you have driven a while. Many tire shops repair simple punctures inexpensively, and they can test and replace TPMS sensors.

Frequently asked questions

Can I drive with the tire pressure light on?

For a short distance, yes, if the tires look normal and the car drives normally. Check and fill the tires as soon as possible. If a tire looks flat or the car handles strangely, stop and put on the spare.

Why does my tire pressure light come on when it is cold?

Tire pressure drops about 1 PSI for every 10°F drop in temperature. On a cold morning a tire that was barely okay goes below the warning point. Add air to the recommended pressure.

What does a flashing tire pressure light mean?

A light that flashes for about a minute and then stays solid usually means a problem with the monitoring system, such as a dead sensor battery, rather than a low tire.

How do I reset the tire pressure light?

Fill all tires to the recommended pressure, then drive for 10 to 20 minutes. If it stays on, check your owner’s manual for a TPMS reset button or menu setting.