Tire pressure monitoring system (TPMS), a feature included on all newer cars produced after September 2007, measures tire pressure either directly by sensors located in the tires or indirectly through wheel speed and other indicators. Your warning lamp will illuminate when data indicates that tire pressure is low.
The indicator can become illuminated for a number of reasons. On cold mornings in Philadelphia, for example, the lamp may be on for a short time, then turn off. This occurs because tire pressure may have fallen overnight...