Short answer
A steady TPMS light means at least one tire is significantly under-inflated. Check all four against the pressure on the driver's door-jamb sticker and add air. A light that flashes for about a minute at start-up and then stays on means the monitoring system itself has a fault, not necessarily a low tire.
- Also shown as:
- TPMS light · Low tire pressure light · Tire pressure warning
- What it looks like:
- A cross-section of a tire, like a horseshoe with a flat bottom, with an exclamation mark inside.
Is it safe to keep driving?
Yes, briefly, unless a tire is visibly flat. Check the pressures at the next stop; an under-inflated tire overheats and can fail at highway speed.
Stop driving now if:
- A tire looks flat or has a bulge, or you hear flapping or thumping.
- The car pulls to one side or the steering vibrates.
- The pressure in one tire keeps dropping after you have filled it.
What causes the tire pressure (TPMS) light?
Most common first. Symbols and meanings vary by manufacturer; your owner's manual has the definitive meaning for your model.
- Cold weather. Tire pressure falls about 1 psi for every 10°F drop in temperature, so the first cold morning of the fall switches on lights across the country.
- A slow puncture or leaking valve. A nail or screw in the tread, a worn valve stem or corrosion where the tire seals against the wheel all let air out gradually.
- Normal air loss over time. Every tire loses some air through the rubber. NHTSA advises checking pressures at least monthly; a tire left alone for months will eventually trip the light.
- Sensor battery or sensor fault. Most systems put a battery-powered sensor in each wheel. When a battery runs down or a sensor is damaged, the light flashes at start-up and then stays on.
- System not reset or relearned. Some cars need a reset after you adjust the pressures, or a relearn after the tires are rotated or new sensors fitted. Until then the light can stay on.
What should you do right now?
- If a tire looks flat or the car pulls or vibrates, stop somewhere safe and fit the spare or call for assistance.
- Otherwise drive gently to the nearest air pump and check all four tires against the pressure on the door-jamb sticker — not the number on the tire sidewall.
- Check them cold if you can — after the car has been parked for a few hours — because driving warms the air and raises the reading.
- Inflate to the recommended pressure. On many cars the light goes out after a few minutes of driving; others need a reset described in the owner's manual.
- Re-check the low tire the next day. If it has dropped again, have it checked for a puncture.
- A light that flashes for a minute then stays on means a sensor fault, not low pressure.
What does the fix usually involve?
A puncture in the tread can usually be repaired from inside the tire with a plug-patch. Damage to the sidewall or shoulder means a new tire.
A leaking valve stem or valve core is replaced; a leak where the tire meets the wheel is fixed by cleaning and resealing the bead.
A failed sensor is replaced and programmed to the car. Shops use a TPMS tool to read each sensor and run the relearn procedure.
How much does it cost to fix?
$0 – $250
Free air at the low end; a puncture repair or a new TPMS sensor at the high end.
A typical range, not a quote. Actual cost depends on the car, the shop and the fault.
Common questions
Why is the TPMS light on when my tires look fine?
A modern radial tire can look normal while being badly under-inflated. US rules require the warning when a tire is about 25 percent below the recommended pressure, and you cannot see that by eye. Use a gauge.
How do I reset the TPMS light?
Set all tires to the recommended pressure first. Many cars then switch the light off by themselves after a short drive; others need a reset button or a menu setting, and some need a shop's relearn tool. The owner's manual gives the procedure for your car.
Should I inflate my tires to the number on the sidewall?
No. The sidewall shows the maximum the tire can hold. The right pressure for your car is on the sticker in the driver's door jamb or in the owner's manual.
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