The Service Tire Monitor System (STMS) is a feature in modern vehicles that monitors tire pressure and alerts the driver if the pressure is suboptimal. The STMS uses sensors in each tire to detect the pressure and sends the information to the vehicles computer system. If the system detects that the tire pressure is too low or too high, it will trigger a warning message on the dashboard. The warning message can mean that the tire pressure is suboptimal and requires adjusting to the recommended pressure, or it can indicate a system problem, like a faulty sensor or a bad battery in the sensor. In some cases, the STMS warning message can trigger the check engine light to come on. If the STMS warning message appears, it is important to check the tire pressure and inflate the tires to the recommended pressure. If the warning message persists, it is recommended to take the vehicle to a certified mechanic to diagnose and fix the issue.