TPMS is a tire-safety system that monitors tire pressure directly or indirectly and alerts the driver when pressure is too low.
Direct vs indirect TPMS
Direct TPMS uses pressure sensors, usually inside each wheel, to measure tire pressure. Indirect TPMS estimates pressure loss from wheel-speed behavior through the ABS sensors.
Direct systems can often show individual tire pressure. Indirect systems may be cheaper and simpler but usually need recalibration after inflation, rotation or tire changes.
What the TPMS warning means
A TPMS light usually means one or more tires are underinflated, or the system itself has a fault. Some vehicles use a steady light for low pressure and a flashing light for a system malfunction.
Check the owner's manual for the exact warning behavior.
TPMS is not a substitute for a tire gauge
TPMS is designed as a warning system, not a daily precision tire gauge. Tire pressure should still be checked when tires are cold, using the recommended pressure on the vehicle's tire placard or owner's manual.
Sensor replacement and resets
Direct TPMS sensors contain batteries and may need replacement after years of service. Tire changes can also require relearning sensor positions or resetting the system.
After changing tires, wheels or pressure, follow the vehicle-specific reset process.
Why TPMS matters
Underinflated tires can reduce handling, braking performance, fuel economy and tire life. In severe cases, low pressure increases heat build-up and failure risk.
Related terms
Sources
- NHTSA - Vehicle safety ratings and TPMS
- NHTSA TireWise - Tires and tire maintenance
- 49 CFR 571.138 - Tire pressure monitoring systems
Feature names, connector support, diagnostic behavior and EV specifications can vary by model year, trim, software version and market. Always verify the exact vehicle documentation before buying, repairing or relying on a feature.