If your vehicle is showing tire pressure light stays on after refilling tires, here are the most likely causes and the parts you'll need to fix each one.
Many vehicles do not automatically detect the new air pressure immediately. They require you to either drive above 20 mph for several miles or press a specific TPMS reset button in the cabin to recalibrate.
TPMS sensors have internal batteries that typically last 5 to 10 years. When a battery dies, the sensor stops transmitting data to the vehicle, causing the light to illuminate (often flashing for 60 seconds first).
Many modern vehicles have a hidden TPMS sensor inside the spare tire. If the spare loses pressure over time, the dashboard light will remain on even if your four main tires are perfectly inflated.
The gauge used to fill the tires may be reading incorrectly, meaning the tires are still under-inflated according to the vehicle's computer. Tires must be inflated to the exact pressure listed on the driver's door jamb sticker, not the sidewall maximum.
If you recently had tires mounted, dismounted, or repaired, the technician may have accidentally broken the fragile TPMS sensor inside the wheel with the tire machine.
Some vehicles do not use sensors in the tires, but instead use the ABS system to monitor tire pressure by measuring wheel rotation speed. A failing wheel speed sensor can trigger the tire pressure light, usually accompanied by an ABS warning light.