Tire Pressure Monitoring Systems (TPMS) are now standard on most modern vehicles, playing a crucial role in keeping drivers safe and vehicles running efficiently. These systems alert you when a tire's pressure drops below the recommended level, helping prevent dangerous blowouts, improve fuel economy, and extend tire life. But what happens when a TPMS sensor itself fails? How can you tell which tire pressure sensor is bad? This comprehensive guide will walk you through the process, from understanding how TPMS works to advanced troubleshooting and replacement tips.