The tire pressure light (TPMS) means one or more tires is at least 25% below spec, a sensor has failed, or the system needs a relearn. Here are the most likely causes ranked by how often they turn out to be the problem.
Cold weather drops pressure ~1 PSI per 10 degree drop. A nail or valve stem leak slowly drains a tire. Always check pressure cold first.
TPMS sensors are battery-powered and last 5-10 years. A dead sensor leaves the system unable to read one wheel.
After rotating tires or installing new ones, the system may need to be retrained to the new sensor positions.
A cracked rubber valve stem or sensor body leaks air. Inspect for cracks, dirt, or moisture corrosion.
On many trucks and SUVs, the spare tire has a TPMS sensor and can trigger the light if low.
A tire is visibly low, you feel pulling or vibration, or you hear hissing when stopped. Driving on a flat damages the tire AND the rim, turning a $20 patch into a $200+ replacement.
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Tire pressure drops about 1 PSI for every 10 degree F drop. A car parked overnight in cold weather often shows the light in the morning.
Battery-powered, typically 5-10 years. The battery is sealed in - when it dies, the sensor must be replaced. Plan for it at 7+ years.
Sensor: $30-$120 each. Labor and relearn: $30-$80. Total per sensor: $60-$200 installed.
After inflating low tires to spec, drive 10-20 minutes. Most cars auto-reset. Some require a manual relearn procedure from the owners manual.
Briefly to a gas station to inflate, yes. Long term, no - low pressure causes blowouts and bad mileage.