Tire Pressure Monitoring Systems (TPMS) have been required since 2008 to alert drivers when a tire is low. The TPMS low-pressure warning light comes on when air pressure inside a tire drops 25 percent below the recommended inflation pressure. If the light is on, the driver should check the tires and add air as necessary.
Direct TPMS systems use a pressure sensor and transponder inside each tire to monitor air pressure. The batteries that power the sensors have a limited service life, typically around 5 years for older first-generation systems, and up to 7 to 10 years for current-generation sensors.
When tires are repaired or replaced, the TPMS sensors also require servicing to maximize the sensors’ usable life. This is a similar process to replacing the traditional valve stems on older non-TPMS equipped vehicles. The difference is that a TPMS service kit is used to replace the hex nuts, cores, caps and seals, or a snap-in stem, depending on the application.
If a sensor has failed, the TPMS malfunction light should come on or flash. NHTSA rules state that an operational TPMS system cannot be intentionally disabled. On the other hand, if the TPMS system is not working, there is no legal requirement to repair it. However, for safe driving a faulty TPMS system should be diagnosed and repaired without delay so this valuable safety system can warn the driver if a tire is low or going flat.
Because of the wide variety of different TPMS systems that are in use today, it takes more than 100 different OEM sensors to cover all of the possible applications. A better solution would be the “multi-application” or “universal” TPMS sensors, which fit a wide range of applications. There are several varieties of these replacement sensors available, and with some product lines only three sensors are needed to cover 85 percent of the replacement market.
Some universal sensors have to be programmed with vehicle protocol software before they are installed (a job that requires a special TPMS tool). Other types are preprogrammed with the vehicle protocol software. However, all TPMS systems must undergo a vehicle “relearn” procedure once the sensors have been installed, regardless of if you are using a universal, multi-application or OE sensor so the system can learn the wheel position of each sensor. On some vehicles, this occurs automatically after driving a few miles. But on most vehicles, there is a specific procedure and sequence with a TPMS scan tool that must be followed.