What does the tire pressure light mean?
What the light is telling you
The Tire Pressure Monitoring System (TPMS) light looks like a horseshoe-shaped tire with an exclamation point inside. When it comes on steady, it means at least one tire is below the recommended pressure—usually by 25% or more—or, in some cars, above it. If it blinks for about a minute then stays on, that often indicates a TPMS sensor or system fault rather than a simple low tire.
Direct TPMS uses battery-powered sensors in each valve stem to measure actual pressure. Indirect TPMS uses the anti-lock brake system to compare wheel speeds and infer a low tire. Both types can trigger the light for reasons other than a puncture, such as cold weather, a slow leak, or a sensor battery dying.
What to do when it comes on
First, don't panic—but don't ignore it. Pull over safely and visually inspect all four tires (and the spare, if your system monitors it) for obvious flats or damage. If a tire looks low, inflate it to the pressure listed on the driver's door jamb or fuel door—not the number molded on the tire sidewall, which is the maximum.
Use a good digital tire gauge to check all tires, including the spare if equipped. If you add air, the light may stay on until you drive a few miles or press a reset button (location varies by model). If the light remains on after inflating and driving, or if it blinks, have the system checked—many tire shops diagnose TPMS for free or a small fee.
- Check pressures when tires are cold (before driving).
- Inflate to the door-jamb placard, not the tire sidewall max.
- Cold weather can drop pressure ~1 PSI per 10°F.
- A blinking light usually means a sensor fault, not just low air.
- Reset the system if your car has a TPMS reset button.
- Don't ignore it—low pressure hurts fuel economy and safety.
Common mistakes
- Assuming the light means a flat tire—it often just indicates slightly low pressure.
- Inflating to the maximum pressure on the tire sidewall instead of the vehicle's recommended pressure.
- Ignoring a blinking TPMS light, which often signals a sensor problem that won't fix itself.
